Licenses

Commonly used open source licenses

Though there are over 50 Open Source Initiative (OSI) approved licenses most of the licenses fall under two categories:

 Academic licenses, such as the Berkeley Software Distribution (BSD) license, allow software to be used for any purpose. Software obtained via an academic license can be freely changed, sold, redistributed, sublicensed, and combined with other software.

 Reciprocal licenses like the GNU General Public License (GPL), also allow software to be used for any purpose, however it enforces that the changed or modified software must also be licensed under the exact terms as the original license.

A GPL licensed code does not allow proprietary software to link to it. It also does not permit redistribution with software having a GPL non-compatible license. Also redistribution of the derivative works need to be with GPL.

On the other hand MIT licensed software allows all of it. It permits proprietary code to link to it, redistribution with non-MIT license software and redistribution of derivative works with non-MIT license. Interestingly, they both are open source software licenses as they follow the open source definition specified by the OSI.