AGPL or Affero General Public License Version is a new License released by FSF. This is aimed at Web Applications.
The GNU GPL allows people to modify the software they receive, and share those modified versions with others, as long as they make source available to the recipients when they do so. However, a user can modify the software and run the modified version on a network server without releasing it. Since use of the server does not imply that people can download a copy of the program, this means the modifications may never be released. Many programmers choose to use the GNU GPL to cultivate community development; if many of the modifications developed by the programs users are never released, this can be discouraging for them. The GNU AGPL addresses their concerns. The FSF recommends that people consider using the GNU AGPL for any software which will commonly be run over a network. (Emphasis mine)
Say I used AGPL for Nexty. You decide that it is a nice program – so you download it and use it. Then you make some changes to the code. So far so good.
Then you decide that you can put the modified version on your web server. The visitors can use the modified version of nexty – that is, you are not ‘distributing’ the software. If I used GPL, you could have gotten away with it – but if I use AGPL, you have to publish the code you modified as well.
The end result is that the end user is in a lot of confusion about what they should do with respect to the license. If they are not lawyers, they will not be able to understand what the license says. I have opted to use the BSD license due to factors like this – BSD license basically gives you the right to do anything with it – except claim that you wrote it.