Free Software Licenses

  • Copyleft software - free software whose derivatives and copies must also be distributed as free software.
  • Non-copyleft free software - Free software whose license allows derivatives to be turned into proprietary software.
FSF"The term “open source” software is used by some people to mean more or less the same category as free software. It is not exactly the same class of software: they accept some licenses that we consider too restrictive, and there are free software licenses they have not accepted. However, the differences in extension of the category are small: nearly all free software is open source, and nearly all open source software is free."

Proprietary Licensing

FSF: "The Free Software Foundation follows the rule that we cannot install any proprietary program on our computers except temporarily for the specific purpose of writing a free replacement for that very program. Aside from that, we feel there is no possible excuse for installing a proprietary program."

Related Terms

  • Freeware - generally refers to software that is distributed free-of-charge, usually in binary. Not the same as free software.
  • Shareware - allows users to share applications with others, but it does not include the source code and usually requires users to pay a fee if they continue using it.

Non-software Licenses