You are here: Home page > About us

About us/FAQ

Last updated: September 21, 2023

You can find contact details for this site at the bottom of this page. Before you shoot off a mail, however, please kindly check this list of frequently asked questions (FAQ). You might find an instant answer and save yourself a lot of time. Thank you.

About this site

Who writes this stuff?

All the articles on Explain that Stuff are written by Chris Woodford, a British science writer with over 25 years of experience in explaining science and technology.

Is this site safe for children?

Yes (hopefully). This is an educational website that I hope is safe and suitable for all family users, though it's mainly intended for ages 10+. I take my responsibility to young readers very seriously:

If you discover anything that you think may be inappropriate for young readers, please alert me straight away and I will try to put it right immediately.

External links

Please be aware that virtually all articles on this site contain links to carefully researched external sites for further reading (and they usually open in a new window so you can tell you're leaving this site):

Why explain stuff that way?

Here's a word or two about my pedagogical approach, for parents, home-schoolers, teachers and anyone else who's interested.

Our survey says...

Most people think science and technology is fascinating, fun, and incredibly important, yet they don't really understand it, even when they've studied it for years in school. How do I know this? Well... consider the findings of two recent surveys:

So people actually do like science and they do find it interesting, but they don't really understand it and they don't feel properly informed about it: somehow it just flies straight over their heads. That may be why so many children convince themselves science is hateful or boring in school... only to discover years later, as adults, that they actually quite like it! Whose fault is all this? I'm not sure—but my mission is to help put things right.

What I try to do is present often quite complex stuff in a way ordinary people can get a handle on. You'll find my articles are a bit different from the ones you get on other websites or in science books: I try to give you a good, clear, simple understanding of a subject rather than drown you in facts, details, and nit-picky trivia. Generally, my approach is to talk you gently around a subject, building on familiar stuff you're likely to understand already, a bit like a decent teacher would do.

Why simplest is best

After studying science for about 35 years, and writing about it for over 25, I firmly believe that it's better to completely understand a small amount about something—the essence of how something works or the science behind it—than to know vast amounts of non-essential details that don't fit together in your mind and don't make sense. In my book (and some people will strongly disagree with this), it's even okay to have a slightly wrong or oversimplified understanding of something than a totally correct misunderstanding. So, for example, I think it's much better if children have a firm, oversimplified understanding that electrons "whiz around" atoms that they can explain to a friend than some sort of fuzzy, confused (but scientifically more accurate) idea about orbitals and probability that they barely understand and could never explain to anyone else. This is not an excuse for dumbing down: it's an argument for teaching with sensitivity—understanding your audience and what they need to know. You can always build on a firm, simplified understanding (or correct, tweak, or qualify it) later on; you can never build on confusion. And if you turn people off too soon, you may well lose them forever. What good is that?

Learning lessons from other websites

This website is not supposed to be anything remotely like Wikipedia—and for a good reason. I value Wikipedia very highly and I think it's an absolutely superb contribution to collective knowledge. But it has serious shortcomings as an educational tool because it fails to take account of a simple fact that is blindingly obvious to any teacher: readers of different ages and abilities have very different levels of understanding and need very different kinds of information. Many Wikipedia articles (especially the scientific and technical ones) are now written by self-professed "experts," for themselves and their friends—people who take too little time to consider how to explain things clearly to general readers (or young students). As time rolls on, simple outline articles ("stubs") become longer and more complete, but they often become more complex and convoluted and harder to understand at the same time. (One of my favorite examples is Wikipedia: Entropy, an article so impenetrable to general readers that it has now spawned an offspring called Wikipedia: Introduction to Entropy, which, in my opinion, now merits its own "Wikipedia: Introduction to Introduction to Entropy" that ordinary people (and students under the age of 18) might just have a hope of understanding. I say this as someone who studied thermodynamics to degree level. That's just one random example. Take a look at Wikipedia: Refractive Index for another example. Lots of great information, if you happen to have a degree in physics, but most of it entirely unsuitable for most of the readers who will look at it—typically, I would guess, younger teenagers seeking homework help.) In short, Wikipedia's problem is that its writers start off from what they're burning to say rather than from what people want and need to know; a good teacher or educator will always start from the audience.

Example of Wikipedia's 'too technical' labeling

Artwork: Wikipedia is waking up to the fact that many of its articles are too complex for general readers. There's now a handy template you can add to flag up the problem for a fix: simply edit the problem section and insert {{technical}} to make this little box pop up in the text. Add a note on the "talk" page, if you wish, explaining why you feel the material you've flagged is "too technical" to understand.

Of course there are plenty of websites besides Wikipedia, but quite a lot of them merely describe gadgets and technologies without explaining them or putting them into a broader context. That's sometimes because the people who write them don't have a rich enough scientific understanding. But it's also because many websites contain vast numbers of bitty articles written by separate authors and, unlike in book publishing, there's no editor to give the whole thing an overall structure and ensure all the articles work together as a coherent whole. My approach is much more book-like. The emphasis here is on gently building knowledge and understanding, not filling people's heads with undigested confusion. Apart from explaining how things work, I try to get across the fundamental scientific principles behind things so you can make the connections, see the patterns, and figure out how everything links together. So while I have (for example) articles about toasters, loudspeakers, and refrigerators, they're also quietly teaching you the science of heat, electromagnetism, and thermodynamics. Learn the basic science behind a few things and you can figure out the technology of quite a lot of other things. This website is book-like in another important way too: I write everything on the site, so I know exactly how all the articles work together. Over a number of years, I've figured out which articles I need to add to make a very comprehensive collection that works as a coherent whole, in much the same way as a printed book. In one important way, the website is very unlike a book: it's being continually revised and improved to take account of new information and feedback from readers. Every article clearly states at the start when it was last updated.

Learning from history

Tech websites have a very unfortunate obsession with newness and fads; Twitter (for all its good points) encourages a tendency to recycle ("share") items of current science news, often making matters worse. How many people who fell over themselves to "retweet" stories about neutrinos breaking the speed of light had the slightest idea why the probability of that scientific finding being correct was so incredibly slim? In sciences such as physics, chemistry, and biology, the core, bedrock stuff you need to learn is years, decades, or even hundreds of years old and much of it will never change. (That's a measure of how excellent the work done by people like Newton, Maxwell, and Einstein really was.) In a subject like physics, the stuff people learned in schools and colleges 50 years ago is still the essence of what children need to understand properly today before they surf the flotsam and jetsam of the new. That's why we can (and should) still read and admire lectures delivered in the 1960s by such great scientist-educators as Richard Feynman; they are just as relevant today. You can't properly grasp any invention, machine, or cutting-edge technology if you don't properly understand concepts like electricity, magnetism, heat, atomic structure, the laws of motion, the kinetic theory, the conservation of energy... and so on. Those are the sort of topics that I drum home on this website, carefully disguising them as articles about interesting everyday things.

Even for cutting-edge science and technology, historical background is really important. That's why there's a full timeline on this site, indexing most of the inventions and discoveries chronologically. Over the last couple of years, I've also come to the conclusion that inventions can be explained more richly by referring to original patent drawings, particularly if they're color-coded and annotated simply. If you want to understand an invention like the laser printer, you can do it by looking at the components inside and seeing how they form a logical sequence. But you can also do it by going back to Gary Starkweather's (the inventor's) original patent and noticing that he invented the laser printer by bolting a laser scanner on top of a conventional photocopier. That explains why laser printers and photocopiers have so much in common. A lot of my articles now contain details of patents to give readers a richer understanding of how things worked and why inventors solved problems a particular way.

Anyway, that's where I'm coming from—and it's quite enough pedagogy for now. In a nutshell: this site is dedicated to helping people learn useful things about everyday stuff in an interesting way. I've spent twelve years (so far) putting it together and I really do hope you enjoy it. If not, do please write and tell me. Good or bad, your feedback is always interesting to me and always welcome.

Your explanation is too complex/too simple!

It's much harder to explain things than you might think. It's not so bad if you're a teacher and you know what children of a certain age range or experience level will understand, but it's harder when you're writing for people you can't see and you don't know what their "frame of understanding" is (how much they know and understand already, what sorts of concepts they're already familiar with, and so on). To be satisfying to someone, an explanation has to make sense within their own frame of understanding. For a better sense of why this is so tricky, allow Richard Feynman to explain.

How does this website support curriculum learning and home-schooling?

You'll find detailed help in my teaching guide, which shows how my articles map to different parts of a typical science curriculum for students aged 10–18.

Why do you only write about science and technology?

I want the material on the website to be of a high standard, so I write about only the things I feel reasonably well qualified or knowledgeable enough to write about: physical sciences, technology, engineering, environmental issues, and computing. To write a really good explanation, you have to understand something very well indeed; when people write about things they don't understand, it's very obvious—and it's not fair on readers. Unfortunately, I don't know enough about life sciences, economics, law, politics, and so on to write well about those other topics. Maybe at some time in the future I will come across someone who can do those things for me.

Why do you spell things the American way?

Although this site has a worldwide audience, more readers come from North America (the United States and Canada) than from anywhere else. For that reason, I do my best to use US editorial conventions (spellings, punctuation, and so on) wherever possible and as consistently as I can. From a publishing viewpoint, that means Webster's spellings and, wherever possible, Chicago grammatical conventions. Occasionally I receive complaints from people who object to words like "aluminum" (on the grounds that that's not the official IUPAC convention) or "meter" (see below) but I'm afraid that's simply the convention I've adopted to satisfy a majority of my readers.

What's with "types of..." and "kinds of..." followed by a plural?

As mentioned in the previous answer, I tend to follow Chicago stylistic conventions on this site because more readers come from North America than elsewhere. For that reason, you'll see headings like "Types of metals" (which tends to make British people bristle), rather than "Types of metal" (which the British would be more likely to write, but would sound odd to many American ears). I don't think there is a definitively correct way of handling this, nor one that is equally acceptable to people in all places, so my solution is to follow my broader convention and do it the accepted American way. If you're interested, here's a bit more about the British grammatical approach to kinds, types, and sorts from the BBC World Service; for a discussion of the American approach, check out p62 of The Columbia Guide to Standard American English (entry "kind, manner, sort, style, type, way").

Why do you use metric units? Why do you spell SI units "meter" and "liter"?

This is a scientific website so I follow the convention of using metric and SI units (such as meters and kilograms), though I generally give Imperial conversions in brackets. Like many US science publications and textbooks, I have decided to follow the US National Institute of Standards and Technology convention, based on Webster's (US English), rather than the Oxford (UK English) convention:

"(i) The spelling of English words is in accordance with the United States Government Printing Office Style Manual, which follows Webster's Third New International Dictionary rather than the Oxford Dictionary. Thus the spellings "meter," "liter," and "deka" are used rather than "metre," "litre," and "deca" as in the original BIPM English text".

Why have you made this article too easy/too hard?

Some people find the articles too easy, some find them too hard. Please bear in mind that a website can't really choose its audience: it has to do its best to cater for whoever happens to be reading, including many reading in languages other than their main one. Generally, the articles are meant to be on the easy side—so you get a good basic grasp of the fundamentals you can fill in with deeper and more detailed material later. That's why almost every article here contains an extensive list of further reading at the bottom.

What font does this site use?

Lovely, isn't it? It's Lato, designed by War­saw-based design­er Łukasz Dziedz­ic.

Using material from this website

Please note that different rights apply to the words and the pictures on this website. Briefly:

Please be aware that you may not use any material from this website to suggest or imply that I endorse or approve of your organization or company, your website, or any product or service you might be developing, producing, or selling. (Relevant United States code here includes 15 U.S. Code §1125—False designations of origin, false descriptions, and dilution forbidden.)

Here's a more detailed explanation if you need it...

Using words from this site

Can you copy and use articles from this website on your own website? No. I'm very sorry, but, excepting "fair use", I do not permit people to copy articles from onto other websites (including blogs, Facebook pages, and other personal sites) for any reason whatsoever (including translation into other languages).

Fair use ("fair dealing"), such as briefly quoting from my articles for purposes of commentary or discussion, is fine, providing you cite this website as the source of your quote. Fair use does not allow you to republish extensive or entire copies of our articles and use them as you wish on other websites, or elsewhere, even if you're doing so for noncommercial or educational purposes. Please note that I will generally regard extensive copying and any unattributed or misattributed quotation (passing my material off as your own) as copyright infringement. Please be aware that all the articles on this website are either registered at the US Copyright Office (or deposited there pending registration), which means deliberate copyright infringement can make you liable for severe financial and even criminal penalties. I routinely scan for unlawful copies of my articles and I take some kind of action in every case of copyright infringement I find. I take copyright infringement extremely seriously and employ law firms in Europe and North America to help me enforce my rights.

The simplest way to avoid any kind of copyright problem or misunderstanding is to ask for permission. Please feel entirely free to contact me if you have any queries, you'd like to discuss reprinting or reusing our articles, or you'd like me to confirm whether some use you have in mind is "fair use" or otherwise okay. I am always happy to help—and generally I'll reply within a day or so.

Using pictures from this site

Can you copy and use our pictures? Broadly speaking, if you're not using them primarily to make money, yes, with pleasure. But do read on.

The photos and artworks on this site fall into three different groups:

  1. Any images and photos used on this website are believed, in good faith, to be in the public domain if they are credited in the caption to US Federal Government agencies such as NASA, the US Patent and Trademark Office, the US Department of Energy, or the US Military (US Army, US Air Force, US Navy, US Marines), or their employees. I have taken reasonable steps to check each image, but I cannot and do not guarantee its copyright status. If you want to reuse one of these photos, it's your responsibility to confirm the copyright status for yourself. In case you're wondering, I have sometimes "cropped," blurred, scrambled, or otherwise disguised people's faces in public domain photos to protect their legal right to privacy. It is my policy to give individual photographers full credit for their work whenever I possibly can and I would suggest you do the same. Please note that wherever US military photos (aka "U.S. Department of Defense (DoD) visual information") are used on this website, the following disclaimer applies: "The appearance of U.S. Department of Defense (DoD) visual information does not imply or constitute DoD endorsement."
  2. I also use a few photos from Flickr and Wikimedia Commons that are published under various Creative Commons licenses. Please note that these photos are still protected by copyright and their owners kindly grant us permission to use them, but only if we follow their conditions (the licence, in other words). If you wish to reuse these photos on your own website, please be sure to follow the licence exactly. Usually that means you have to credit the original photographer (which is only fair) and repeat the licence, but there may be other stipulations (such as not creating modified or "derivative works"). If you're not sure, copy the exact words I've used to credit the photographer and the link to the Flickr and Creative Commons websites and you should be OK. (I return the favor to the Flickr community by offering more of my own photos for reuse than I use from Flickr. You'll find them on our Flickr page, all published under a Creative Commons licence.)
  3. Creative Commons License Any photos or artworks that are not attributed to other people or agencies are ones I have created and you're welcome to use and reuse them for noncommercial purposes only under the terms of the Creative Commons NC-SA license. For the avoidance of doubt, please note that "noncommercial" means you may not charge a fee for the use of my work, use it in any for-profit publication (whether educational or not), use it to sell, endorse, or promote any product or service, or earn any money from it by advertising or any other means whatosever, irrespective of whether you make a profit. Hi-res versions of a few of my photos are available for commercial use, under license, on our Flickr page; other photos are available in high resolution on request. Please would you kindly attribute any images I've created by crediting "Chris Woodford" and/or "" and, if you wish, optionally, making a link to the page on my website where the original image appears (a "nofollowed" link is perfectly fine) so that people can find out more if they care to. Some HTML along these lines would be just great, thanks:

    Image from <a rel="nofollow" href="">Explain that Stuff</A> published under a <a href="">Creative Commons License</a>.

    Or, if you prefer to do it without the link, which is absolutely fine, you can do it like this:

    Image from Explain that Stuff published under a <a href="">Creative Commons License</a>.

Hotlinking to pictures from your pages

If you would like to use images from this site, you'll need to copy and upload them to your own server rather than linking directly to them ("hotlinking"). Please note that image hotlinks to are automatically blocked and will return a 403 "Forbidden" access code. If you link to my images directly from your own pages, you'll find a blank space instead of the picture you actually want. If you meet the criteria for reusing images up above, please ensure you host them on your own webspace.

Would you like to license photos or artworks for commercial use?

Privacy and cookies policy

You'll find the full privacy and cookies policy for this website on the privacy policy page.

Do you give permission to reprint material in books and educational publications?

Yes, but you must ask for written permission in every case. Since this website is all about science education, I'm happy to discuss requests for limited reuse of material from this website in educational books and other materials, but (as explained above) not on other websites or in any other material that appears online (unless it's behind a password-protected login).

Please kindly send me details of your publication, intended audience, approximate print run, publisher, and anything else you think might be relevant, and specific details of the material you'd like to use, and I'll let you know what's possible (usually the same day). Please note that if you are a commercial publisher, or your use is primarily commercial (for profit), I will normally charge a licensing fee; that usually includes self-published books (e.g. self-publication through Amazon). If you're a very small, educational publisher producing low-volume books only for schools, the licensing fee is normally reduced by 50 percent. If you're a registered nonprofit/charity organization (for example, a 501(c)(3) in the USA or a registered charity in the UK), I don't normally charge a licensing fee unless you are, yourself, charging for your publication or publishing in high volume, but you will still need to request permission. Please see my licensing page for more details about licensing fees and commercial use. If you're unsure, please just send me details of your specific case.

Please note that magazines and other material produced by business/trade organizations fall within my definition of commercial publications: if you charge a membership fee (even if you are a registered nonprofit) you will need to license articles, just like any other commercial organization, and pay a licensing fee.

Will you give us a substantial discount or let us license your articles for free in our book?

No, unless (as above) you are a very small educational publisher or a nonprofit/charity. If you're a commercial publisher and you want to license work from me, please expect to pay commercial rates.

How (and when) should I cite your articles?

When to cite

It's often a good idea to acknowledge the source of articles you use—and absolutely required by many schools, colleges, and other academic instutitions. If you're quoting verbatim from something, citing a source is the way to avoid problems of plagiarism (though the golden rule is that it must absolutely clear to readers which work is your own and which is other people's); it's also generally a requirement if you're claiming "fair use" (fair dealing) of copyright material. The way to cite a web page varies according to the citation style you're using (if no-one has told you which style to use, it doesn't matter). All of our articles have ready made cut-and-paste citations at the bottom of the page, which you can modify as you wish. For example:


For example:

If your citation style or educational organization requires you to specify a "city" of publication, you can quote that as London, England if you want to.

Like articles on Wikipedia, all the articles on this website are in a state of continuous improvement and I try to check everything at least once a year. Quite a few of the articles now contain two dates in the citation, so you might see something like "(2007/2016)." The first date indicates when the article was originally published; the second date indicates the most recent substantial revision. Every article also has a note at the top showing when it was "last updated." That can mean anything from a simple check that the links were correct or the addition of some new suggestions for further reading to a complete rewrite. When an article has only minor updates, I change the date at the top, but not the date in the citation. Just because an article contains an older date in the citation, it doesn't follow that it's out of date: some information never dates.

What reference sources do you use?

Some of my articles have extensive lists of citations and references at the end; some have appropriate inline citations (links to other sites); some have no citations at all. The reference sources I use vary from one article to another, but I only ever use the most authoritative and reputable sources I can find.

For simple general articles (things like how electric motors work or what magnetism is all about), I write without resources, because I know the subject well enough to do that; that's why there are few or no citations in those pieces. For technical topics, I generally use manufacturer's information or patents and, where possible, take things apart to figure them out. Generally, I use books written by academics or noted experts rather than random Internet sites. For more "topical" (newsworthy) topics, I use the most authoritative sources I can find, depending on the subject matter. For example, on climate change, I would use the IPCC (the most authoritative scientific body), government sources, very reputable news sources, and so on. It's easier to say which sources I don't use: typically, I don't use Wikipedia as a source (except as a jumping point to other material) unless I can verify for myself that the material is correct with at least one other source; I don't use "popular journalism" (other than in excellent, authoritative sources such as IEEE Spectrum or The New York Times); and I don't use random websites unless it's clear they're "expertly well informed." If there's a specific article you're interested in, and you're unclear about some of the information I've included, please contact me and I'll be happy to clarify for you where the information came from.

Importantly, every page on this website carries a request for feedback from readers. Over the years, I've received almost 4000 expert suggestions and corrections from ordinary readers, university professors, product designers, and even the family members of famous inventors, and (after very careful checking) these ideas are almost always incorporated into my articles. While this isn't quite "peer-review" in the academic sense, reader feedback—this process of constant review, addition, and improvement—is another important source of material for this site.

I am a teacher. Can I print and use material from this site in class handouts?

Yes. If you are a teacher or professional educator, you are most welcome to print and circulate up to 100 copies of my articles as a handout for your classes within your own school or college (only), providing you do so for free. You do not need to ask permission, but please kindly credit this website as your source. I consider this a "fair use" and —as someone firmly dedicated to science education—something I warmly endorse and encourage. However, please kindly do not copy articles verbatim onto publicly accessible school or educational websites. If you are a teacher and you would like higher resolution versions of art or photos for handouts, please do get in touch; I may well be able to help. If you would like to print more than 100 copies, you will need to pay a small educational licensing fee, which I will generally donate to a charitable organization. If you'd like high resolution artworks or photos for school use, please feel free to send me an email and I'll see what I can do.

I am a teacher. Can I upload an article from this site to [some educational system]?

No, sorry. For various technical, legal, and practical reasons, I don't permit the use of articles from this site on other websites, educational databases, or electronic educational systems of any other kind, whether they're publicly accessible or not.

I am a student teacher. Can I produce "derivative material" for training purposes if I don't republish it?

Yes, with the following qualifications: Student teachers sometimes have to develop their own class materials, based on pre-existing texts, as part of training assignments. I've received a few requests asking if student teachers can use articles, modify the wording, shorten things, simplify them, add or remove photos, and so on. Broadly speaking, as long as you are not going to publish this material anywhere—it's only for your own course—you're welcome to do this, but please be sure to credit the original material somewhere to avoid charges of plagiarism. If you want to use material from this site as handouts in real class settings, please see above. If you need better (higher-resolution) versions of photos and artworks for your materials, please ask and I'll help if I can.

I am an educational organization. I believe I already have the right to use [some material] according to the copyright laws in my country

This website exists entirely for educational purposes—everything here is free to use for everyone in the world with Internet access—and it costs a lot of money to run and maintain. When people copy material from this website onto other websites, it can create technical and legal problems that undermine my ability to keep the site viable; it also creates inferior, substitute copies that I cannot update and improve. From time to time, I receive emails from school examination bodies and other curriculum authorities that begin by notifying me that they consider copyright laws in their country give them an automatic right to reuse copyright registered material from this website as they see fit, including republishing it on the Web. Sometimes, this can create real problems with search engines that confuse the copied material with the original; in some cases, they might preferentially "rank" the inferior substitute and suppress the original. While I'm sympathetic to educational reuse of my material, I do have to consider these issues very carefully. National laws do not, so far as I can see, automatically confer any right to publish globally on the World Wide Web—especially when they predate the Web's very invention. If I consider any use of my copyright material infringes my rights in my own country or internationally to the extent that it could undermine the purpose of this site, please be advised that I will take appropriate action in appropriate jurisdictions, including having material removed from search engine indexes or servers hosted in countries where I consider any claim of rights under specific national laws does not apply.

I am making museum exhibits. Can I use material from this site in my static display?

If you are a nonprofit or charitable museum, you are welcome to use artworks from this website for noncommercial purposes according to the terms described above. I have higher-resolution versions of many of my own artworks and photos, and I can usually locate hi-res versions of the public domain material I've used as well; please feel free to contact me if you need help. If you are a nonprofit or charitable museum, you can adapt short extracts of articles for use in static museum displays providing: 1) You do not publish this material in any commercial or for-profit publications (books, ebooks, CDs, websites). 2) You do not use more than 250 words of text from any article in any one display; 2) You credit the material to "" somewhere on the display. Please note that if you are a commercial museum, you will need to license articles, just like any other commercial organization, and pay a licensing fee.

I am a student. Can I use material from this site in my assignment?

Yes. You are welcome to use short extracts of articles from this website in your school or college projects, providing they are for submission only to your teacher, professor, or course assessor and not for publication (in books, magazines, other publications, or on other publicly accessible websites). I consider this a fair use—and something I would warmly endorse and encourage. However, please be sure to cite what you use to avoid any risk of getting yourself into trouble for plagiarism (passing other people's stuff off as your own). There is a general-format citation at the bottom of each article you can copy or modify into your school or college's preferred citation style, as you wish. But a mere citation is not enough to avoid charges of plagiarism: it must always be absolutely clear to readers which work is your own and which is other people's.

I am a government user. Will you grant extra rights for my publication?

No. I treat government publication requests the same as any other. Occasionally I am asked by government agency employees whether they can incorporate copyright material from this site into their (public-domain) publications. As far as I am aware, government reproduction of copyright material is not automatically a fair use though (you can see from that link) this is a complex issue. If you want to incorporate copyright material from this site into a public domain government work, you can avoid any future problems by asking permission first and, if it's granted, explicitly identifying the relevant material as copyright in your larger, public domain work. (The normal license terms apply to Creative Commons licensed images.) Your use of any copyright material does not change its copyright status—so it does not become "public domain" simply because your larger government work is public domain (for example, because of 17 US Code § 105).

I am editing a local community newsletter. Can I reprint an article in it?

Yes, on the following conditions: 1) You do not charge people money for the newsletter or make money from it on a commercial basis (for example, by advertising); 2) It is published only in print format and not uploaded to any website or made available online; 3) You do not print more than 250 copies. That means "community newsletter" does not include "local newspaper given away for free but paid for by advertising." 4) You credit me/this website somewhere in the article and don't pass off the material you use as your own. If you have any queries, or you'd like to vary any of these conditions, please feel free to contact me for permission.

Can I use material from this site inside my company (purely for an internal audience)?

Subject to the restrictions noted here, yes. If you're producing educational material for use purely inside your own company or corporate group (not for any kind of general external or customer publication), you may print and circulate up to 100 copies of any one article from this site as a handout (or related teaching material), providing you do so for free. You do not need to ask permission, but please kindly credit this website as your source. However, if you'd like to reproduce any material in any publicly accessible form (such as customer literature), you must seek permission first and (usually) enter into a licensing agreement, for which you will normally be charged a licensing fee. Please kindly note that I do not give permission for the reuse of material from this site on company websites for any reason whatsoever and any unauthorized use will be regarded as copyright infringement (fair use excepted, such as briefly quoting from my articles for purposes of commentary or discussion).

Can I translate your articles into another language and republish them?

No. Translations are derivative works; in other words, you must obtain permission to translate things. I do not permit translation of articles from this website into any other languages either for online or offline use for free. If you would like to translate and republish something purely for offline use (in a book or other printed publication), you will need to enter into a licensing agreement and pay an appropriate licensing fee. Please note that I do not allow reuse of articles from this site on other websites, either in English or in any other language, for any reason whatsoever. Also, please be aware that if you use automatic translation to translate information from this or any other site, Google is likely to remove your site from its index for violation of its Webmaster Quality Guidelines on autogenerated content. Please also be aware that when I find unauthorized translations, I treat them as copyright infringement.

Can I make an app or YouTube-type video from your website?

No. It's quite likely that I will do this myself at some point in the future. Sorry, I will not reply to speculative emails from app and video developers. I will view unauthorized apps and videos as a copyright infringement.

Can I frame articles from this site on my website?

No. A number of legal cases have ruled that framing is a copyright violation, and we use a technical mechanism to block it.

Copyright and legal information

You'll find this on the copyright and legal notice page.

Can I tell you all about my great new invention?

No, sorry, I will not help with inventions or give advice about their scientific/technical feasibility.

Can I hire you as a consultant to help develop my invention?

No, sorry, I don't do this kind of work. However, I can often suggest experts in particular areas or companies who might help.

I have a great idea. Where can I get help with patents and so on?

There are some good, general reading suggestions (for adults and children) at the end of my article about inventors and inventions. The US Patent and Trademark Office has a good collection of resources for inventors (including details of how to patent and trademark things) and the European Patent Office has a handy inventors' handbook. The USPTO also has a good kids page.

Do you have any advice for young scientists?

Yes. A few years ago, I wrote a page of very general advice on how to be a scientist. It has links to many sites offering advice about STEM studies and careers.

Will you mentor our science project or science club?

I get quite a few requests to help schools and community clubs with things like First LEGO League projects, science fair projects, and so on. Unfortunately, because I live in the UK, it's not really possible to give hands-on practical help to groups in other countries. If you'd like to discuss your ideas informally, that might be possible, so please feel free to contact me and I'll see what I can do!

If you are in the UK, the best place to seek help with something like this is the excellent STEM Ambassadors scheme, which connects properly vetted people working in science, technology, engineering, and math with schools and community groups who need help. For help with computing and robotics projects, try Code Club (UK) or Code Club (World) (all other countries).

Can I interview you for my school project?

Yes, if I know enough about the topic, although if you've been researching an area for a while, you may already know more about it than I do—so maybe I should interview you? Either way, feel free to contact me. If I can't help, I can probably suggest someone else you can talk to. Please send me details and let's see what we can do.

How to advertise on this website

We only accept advertising through Google; you can purchase space on our site and target our pages using Google Adwords, in the usual way. Sorry, but we don't accept any direct advertising and there are absolutely no exceptions to this. does not sell links: you cannot pay to place text links anywhere on this site (even "nofollowed" ones). I do not, never have, and never will sell links and I will not reply to any emails I receive asking to buy links.

Why is your website running intrusive advertisements that seize control of my computer?

As far as I know, it isn't. This website runs as little advertising as it possibly can (two or three relatively small ad ads) to help pay its costs. It runs only conventional advertisements and nothing more intrusive than video. Occasionally, people contact me to say that they have seen very intrusive or distracting advertising while viewing this site. does not run intrusive advertising of this kind. There are no pop-up or pop-under ads, no ads that seize control of your browser, and no exit-type or "sneaky redirect" ads that redirect you to another site. If you're seeing ads like this, it means your browser or computer has been hijacked by malware (malicious software). You need to run antivirus and anti-malware scanners immediately.

Google is our main ad provider and you can also report bad advertisements directly to them using this form. Thank you.

I've been annoyed or offended by an advertisement on your site

Compared to similar websites, this site runs an absolute minimum amount of advertising to help pay the cost of developing it. Advertisements are currently run for Explainthatstuff by Google's Adsense system (several million ads each month). I have no direct control over exactly which ads run, or when they do so, though I have blocked a number of broad categories of advertising that I consider inappropriate for an educational site. I can block irritating, annoying, or unsuitable ads, but, unfortunately, only after they have started running and only when people make me aware of them. If you see something that bothers you, please accept my very sincere apologies. Please kindly send me details (better still, a screenshot of the ad if you can possibly manage that) and I will try to block it from running on the site at the earliest opportunity.

You can also report bad advertisements directly to Google using this form. Thank you.

Would you like to switch your advertising to our network?

No. Thank you for considering this site, but I am very definitely not interested in using any other advertising providers at this time and I will not run trials of other ad networks. I'm very sorry, but I will not reply to speculative emails from advertising providers. I get at least a dozen of these every single week and never read beyond the first few words. It's amazing how many advertising companies assume that making more money from advertising is my main objective (it isn't) and don't bother to read the "I'm not interested" messages I've posted on my contact page. If you can't be bothered to research a website and find out the most basic things about it, such as the reasons why it exists, why could you possibly imagine you'd make a good business partner?

Would Explain that Stuff like to join my affiliate scheme?

No. I am not interested in affiliate schemes, referrals, or any other remotely similar programs.

Will you review my product?

No. Sorry, I don't do product reviews.

Link policy

The answer to almost every question I receive about links is no.

Do I need permission to link to

No. The whole point of the World Wide Web is about making links between related information; as far as I am concerned, you do not need to ask permission to make a simple link to pages on this website (or any other website) though opinions do still vary on this. If you have a corporate/organizational policy that requires you to seek permission before making such a link, please cite this web page as your permission. You may, however, need permission to reuse any material from this website in printed documents, electronic books, or on other websites. Please see Can I use material from this website on my own website? Please note that you may not frame pages from this site on other sites.

I'd like to buy this website/domain. Is it for sale?


Do you endorse the products you write about or photograph?

No. This website contains photographs of real-world products purely for illustrative purposes and occasionally mentions products and brands in the text by way of example. There are absolutely no "product placements." Most of the products in my photos are things I happen to own—so they're quick and easy to photograph. I love some of them; I hate some of them; I photograph them either way if they illustrate a point I'm making. The inclusion of a photograph, or textual reference to a product or brand, in an article does not represent any endorsement by me of the product or brand or any endorsement by the product manufacturer or brand owner of this website or anything we may say in the text. In line with the US FTC Guidelines on Endorsements, I am happy to clarify that I have never accepted (and will never accept in the future) any money, gifts, or anything else of any kind from any companies or individuals in return for writing about or otherwise featuring products on this website. If you are the manufacturer of a product and you'd prefer it not to be featured in one of our photos, please contact me.

Will you syndicate your articles to us to publish on our site?

No. I'm very sorry, but I am not interested in syndicating articles to other websites. I do not allow my material to be copied or published by other websites for any reason (other than legitimate "fair use") and I will take action against unlawfully copied material whenever I find it.

Will you license your articles to us to use offline?

Maybe. Please see the licensing page for more details.

How do I license a photo/artwork for commercial use?

Please see the licensing page for more details.

Do you accept articles or submissions written by other people?

No, sorry, you cannot write or produce things for this site. No articles, no infographics, no nothing. I publish only my own material. There are absolutely no exceptions to this. None whatsoever. I am not interested in publishing articles or infographics by anyone else, for any reason, even if they're supplied for "free."

Will you write something for me?

Maybe. If you're a nonprofit organization and you're doing work in STEM or environmental education, please do get in touch. If your project's interesting and involves something I know about, and I have some free time, I might be able to help. If you're a company and you'd like me to write some sort of promotional, commercial, or technical material for you, I'm sorry, but it's unlikely that I will be able to help; although I used to work as a copywriter, I no longer really do marketing, promotional, or other essentially commercial work.

I'm a journalist looking for an expert. Can I interview you?

Yes, please send me a message through the email form.

Can I subscribe to your email list for updates?

No, sorry, there is no email list for this site. Please follow us on Facebook for general news and updates. I don't add very many new articles to this website anymore; instead, I concentrate on making the existing articles better and keeping them up-to-date.

Are you on Twitter?

No, but we are on Facebook. Any Twitter account purporting to be us is an unauthorized fake.

What does your logo mean

It's supposed to be a stylized representation of a person showing you something or explaining it to you. It's drawn so that it could be a woman, man, or child of any age or race. Check out some clip art of a person explaining and you should get the idea.

How environmentally friendly is this website?

Hopefully, it's pretty good. The site has four separate kinds of energy impact and I've reduced everything in my control:

Would you please remove me from your email list?

As it says very clearly in the privacy policy, Explain that Stuff doesn't collect information about you and there is no "email list" from which you can be removed. If you receive a spam email claiming to originate from, it's a fake; I do not send bulk/spam emails. Similarly, if you receive any kind of "phishing" email from asking you for personal information, that's a fake too; I don't send any emails of this kind. Check the full headers on the email and you'll find the originating domain has been forged. Unfortunately, as banks and other organizations around the world have found, there's little or nothing to stop people from sending forged emails—and certainly nothing I can do about it; please simply delete the mail... and move on.

Contact us

Before emailing, please quickly check that your question hasn't already been answered in the FAQ up above; it will save you time.

Found a mistake?

If you find any errors or inacccuracies in any of the articles, if something really confuses you and you think I should reword it, or if you'd like to suggest any other improvements, please do get in touch. I'd be very pleased and grateful to hear from you. I do my best to fix simple mistakes immediately (if I possibly can, within minutes of people bring them to my attention).

You can send me a general email or media request using the email form; to send feedback on an article, please use the feedback form. Thanks! It's not always possible for me to reply in detail to every single question and query, but I do read, carefully consider, and act on all the feedback.

More to explore on our website...

Back to top