Free software licenses

A free software license is a notice that grants the recipient of a piece of software extensive rights to modify and redistribute that software. These actions are usually prohibited by copyright law, but the rights-holder (usually the author) of a piece of software can remove these restrictions by accompanying the software with a software license which grants the recipient these rights. Software using such a license is free software (or free and open source software) as conferred by the copyright holder. Free software licenses are applied to software in source code as also binary object code form, as the copyright law recognizes both forms.

In the early times of software, sharing of software and source code was common in certain communities, for instance academic institutions. Before the US Commission on New Technological Uses of Copyrighted Works (CONTU) decided in 1974 that "computer programs, to the extent that they embody an author's original creation, are proper subject matter of copyright", software was not considered copyrightable. Therefore, software had no licenses attached and was shared as public domain software. The CONTU decision plus court decisions such as Apple v. Franklin in 1983 for object code, clarified that the Copyright Act gave computer programs the copyright status of literary works and started the licensing of software.

Free software licenses before the late 1980s were generally informal notices written by the developers themselves. These early licenses were of the "permissive" kind.

In the mid-1980s, the GNU project produced copyleft free software licenses for each of its software packages. An early such license (the "GNU Emacs Copying Permission Notice") was used for GNU Emacs in 1985, with subsequent revisions in 1986, 1987 and 1988 taking the name of "GNU Emacs General Public License". Likewise, the similar GCC General Public License was applied to the GNU Compiler Collection, which was initially published in 1987. The original BSD license is also one of the first free software licenses, dating to 1988. In 1989, version 1 of the GNU General Public License (GPL) was published. Version 2 of the GPL, released in 1991, went on to become the most widely used free software license.

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