What Source Code License to use for your project?

Question

I am starting this question to try and make a central point developers can use to choose what Source Code License to use for their projects.

What I am looking for out of this question are the following for the Licenses:

1. A short description of the License
2. What type of projects should this License be used for
3. Examples of existing projects that use this License

Some of the Licenses that I have in mind are the following:

• Apache License 2.0
• Artistic License/GPL
• Eclipse Public License 1.0
• GNU General Public License v2
• GNU General Public License v3
• GNU Lesser General Public License
• MIT License
• Mozilla Public License 1.1
• New BSD License

Answer 1

the two most used licences are GPL and MIT/BSD. To choose between the two, ask yourself the following questions:

• are you using any GPL code? then use GPL
• are you writing in the context of an existing community? then use the community's favored license
• do you want it to be used by anybody? then use MIT/BSD
• do you want it to be used only on Open Source projects? then use GPL
• is it server software, and you want any user to contribute, even if they use it only on their own servers? then use GPL v3

and these are the short (very short) descriptions of the licenses themselves:

• MIT/BSD: anybody use for anything. the most you can ask for is attribution.
• GPL v2: if anybody else (other than you) wants to use in another project, the whole project would be GPL. if anybody else writes enhancements/extensions/changes, they have to publish the changes if they distribute the resulting software.
• GPL v3: like v2; but if they enhance your software they have to publish the changes, even if they don't distribute the software but only use on a public server.
• LGPL: midway between GPL and BSD, mostly for libraries. if anybody use it for a project, the whole project don't have to be GPL; but if they modify the library itself (and distribute the result), they have to publish the changes.