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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 licence is free software as conferred by the copyright holder. Some free software licenses include "copyleft" provisions which require all future versions to also be distributed with these freedoms. Other, "permissive", free software licenses are usually just a few lines containing the grant of rights and a disclaimer of warranty, thus also allowing distributors to add restrictions for further recipients. While historically the most widely used FOSS license has been the GNU General Public License v2, in 2015 according to Black Duck Software as also GitHub statistics, the permissive MIT license dethroned the GPLv2 to the second place while the permissive Apache license follows already at third place. ==History== Free software licenses before the 1980s were generally informal notices written by the developers themselves. At that time, sharing of software was common in certain developer communities and there were even questions about whether copyright law applied to software, so licenses weren't written with a view to having to be defended in court. Copyleft not yet having been invented, these early licenses were of the "permissive" kind. In the mid-1980s, the GNU project produced individual 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,〔(【引用サイトリンク】title=GNU Emacs Copying Permission Notice (1985) )〕 with subsequent revisions in 1986, 1987 and 1988 taking the name of "GNU Emacs General Public License".〔(【引用サイトリンク】title=Free Software - GPL Enforcement )〕 Likewise, the similar GCC General Public License was applied to the GNU Compiler Collection, which was initially published in 1987.〔(【引用サイトリンク】title=GCC Releases )〕〔(【引用サイトリンク】title=GPLv3 - Transcript of Richard Stallman from the second international GPLv3 conference, Porto Alegre, Brazil; 2006-04-21 )〕 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.〔(Top 20 Most Commonly Used Licenses in Open Source Projects, Black Duck Software ).〕 Starting in the mid-90s and until the mid-00s, a trend began where companies and new projects wrote their own licenses, or adapting others' licenses to insert their own name. This license proliferation led to problems of complexity and license compatibility.〔(Report of License Proliferation Committee and draft FAQ, Open Source Initiative 2007-12-12 ).〕 One free software license, the GNU GPL version 2, has been brought to court, first in Germany and later in the USA. In the German case the judge did not explicitly discuss the validity of the GPL's clauses but accepted that the GPL had to be adhered to: "If the GPL were not agreed upon by the parties, defendant would notwithstanding lack the necessary rights to copy, distribute, and make the software 'netfilter/iptables' publicly available." Because the defendant did not comply with the GPL, it had to cease use of the software.〔(【引用サイトリンク】title=Groklaw - The German GPL Order - Translated )〕 The US case (MySQL vs Progress) was settled before a verdict was arrived at, but at an initial hearing, Judge Saris "saw no reason" that the GPL would not be enforceable.〔See ''Progress Software Corporation v. MySQL AB'', 195 F. Supp. 2d 328 (D. Mass. 2002), on defendant's motion for preliminary injunction.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Free software license」の詳細全文を読む スポンサード リンク
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