The MIT License is a permissive license that is short and to the point. It lets people do anything with your code with proper attribution and without warranty.
jQuery and Rails use the MIT License.
The Apache License is a permissive license similar to the MIT License, but it provides a patent license for any code that infringes on a contributor’s patents.
Apache, SVN, and NuGet use the Apache License.
The GPL (V2 or V3) requires that folks who modify your code also license their changes under the GPL. V3 is similar to V2, but adds a restriction restricting use in hardware that forbids software alterations.
Linux and Git use the GPL.