Appropriate legal notices
The GNU General Public License (GPL) is intended to guarantee the freedom to share and change all versions of a program--to make sure it remains free software for all its users. When you receive a program that is licensed under the terms of the GPL, you should receive (or be offered) the corresponding source code along with a copy of the GPL itself.
However, the way people download and install software these days, it is often the case that certain "details," such as the license of the software or offers of source, will go unnoticed by users. So if a user doesn't look at the license or read the page where they are downloading it from carefully, how else will they know that the program is licensed under the terms of the GPL, and what that means?
One answer is: Appropriate Legal Notices. In version 3 of the GPL, it states that if a program has an interactive user interface, then it must display Appropriate Legal Notices, which the GPL defines as:
"An interactive user interface displays 'Appropriate Legal Notices' to the extent that it includes a convenient and prominently visible feature that (1) displays an appropriate copyright notice, and (2) tells the user that there is no warranty for the work (except to the extent that warranties are provided), that licensees may convey the work under this License, and how to view a copy of this License. If the interface presents a list of user commands or options, such as a menu, a prominent item in the list meets this criterion."
So when creating and distributing your own free software programs, consider incorporating Appropriate Legal Notices into your UI (such as in a menu item or elsewhere). But don't just follow the letter of the GPL, consider the spirit of it as well. After all, our goal isn't to hide our legal notices as many proprietary programs do in fine print and complicated language with the hope users will not notice or understand it. In fact, we want to do just the opposite! Let users know that they have the freedom to make, use, improve, and share improvements to the program.
You may be asking how exactly should you word your legal notice so it does all this. Well, I'm not sure there is any one best answer. I would be interested to know what others think. You can help me collect good examples or ideas by either emailing firstname.lastname@example.org with your suggestions or by adding them directly to our LibrePlanet wiki page at: u.fsf.org/14t.