General Public License (GPL)

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The General Public License (GPL) is a license for free software as expressed by the principles of the Free Software Foundation (FSF).

• derivative work must be released under the GPL
  • making a copyleft license

Versions

• GPLv2 released in 1991
  • used by Linux kernel
    • allows use of GPL Linux in fairly closed devices (e.g., Android)
• GPLv3 released in 2007
  • to close some loopholes in v2
  • contains clauses to combat use of hardware restrictions that limit the FSF’s four freedoms and to address issues related to software patents

Lesser General Public License (LGPL)

The Lesser General Public License (LGPL) is a variant of GPL often used with libraries that enables software that uses a library (or LGPL licensed program) to be released under a different license.

• libraries are collections of code that can be used by other programs
• is not copyleft

GNU Free Documentation License (FDL)

The GNU Free Documentation License (FDL) is a license intended for use in documentation.

• GPL was written for software, so doesn’t apply well to static documents
• FSF created FDL to fill the gap
• used by Wikipedia