10 Big Myths about copyright explained An attempt to answer common myths about copyright seen on the net and cover issues related to copyright and USENET/Internet publication. - by Brad Templeton
Note that this is an essay about copyright myths. It assumes you know at least what copyright is -- basically the legal exclusive right of the author of a creative work to control the copying of that work. If you didn't know that, check out my own brief introduction to copyright for more information. Feel free to link to this document, no need to ask me. Really, NO need to ask. [but I will put the link at the bottom so that you know where I got it from]
1) "If it doesn't have a copyright notice, it's not copyrighted." This was true in the past, but today almost all major nations follow the Berne copyright convention. For example, in the USA, almost everything created privately and originally after April 1, 1989 is copyrighted and protected whether it has a notice or not. The default you should assume for other people's works is that they are copyrighted and may not be copied unless you know otherwise. There are some old works that lost protection without notice, but frankly you should not risk it unless you know for sure. It is true that a notice strengthens the protection, by warning people, and by allowing one to get more and different damages, but it is not necessary. If it looks copyrighted, you should assume it is. This applies to pictures, too. You may not scan pictures from magazines and post them to the net, and if you come upon something unknown, you shouldn't post that either.
2) "If I don't charge for it, it's not a violation." False. Whether you charge can affect the damages awarded in court, but that's main difference under the law. It's still a violation if you give it away -- and there can still be serious damages if you hurt the commercial value of the property. There is a USA exception for personal copying of music, which is not a violation, though courts seem to have said that doesn't include widescale anonymous personal copying as Napster. If the work has no commercial value, the violation is mostly technical and is unlikely to result in legal action. Fair use determinations (see below) do sometimes depend on the involvement of money.
3) "If it's posted to Usenet it's in the public domain." False. Nothing modern and creative is in the public domain anymore unless the owner explicitly puts it in the public domain(*). Explicitly, as in you have a note from the author/owner saying, "I grant this to the public domain." Those exact words or words very much like them. Some argue that posting to Usenet implicitly grants permission to everybody to copy the posting within fairly wide bounds, and others feel that Usenet is an automatic store and forward network where all the thousands of copies made are done at the command (rather than the consent) of the poster. This is a matter of some debate, but even if the former is true (and in this writer's opinion we should all pray it isn't true) it simply would suggest posters are implicitly granting permissions "for the sort of copying one might expect when one posts to Usenet" and in no case is this a placement of material into the public domain.
It is important to remember that when it comes to the law, computers never make copies, only human beings make copies. Computers are given commands, not permission. Only people can be given permission. Furthermore it is very difficult for an implicit licence to supersede an explicitly stated licence that the copier was aware of. Note that all this assumes the poster had the right to post the item in the first place. If the poster didn't, then all the copies are pirated, and no implied licence or theoretical reduction of the copyright can take place. (*)
Copyrights can expire after a long time, putting something into the public domain, and there are some fine points on this issue regarding older copyright law versions. However, none of this applies to material from the modern era, such as net postings. Note that granting something to the public domain is a complete abandonment of all rights. You can't make something "PD for non-commercial use." If your work is PD, other people can even modify one byte and put their name on it. You might want to look into Creative Commons style licences if you want to grant wide rights.
http://www.templetons.com/brad/copymyths.html