Copyleft is the practice of granting the right to freely distribute and modify intellectual property with the requirement that the same rights be preserved in derivative works created from that property. Copyleft in the form of licenses can be used to maintain copyright conditions for works ranging from computer software, to documents, art, scientific discoveries and even certain patents.
Copyleft software licenses are considered protective or reciprocal in contrast with permissive free software licenses, and require that information necessary for reproducing and modifying the work must be made available to recipients of the software program, or binaries. This information is most commonly in the form of source code files, which usually contain a copy of the license terms and acknowledge the authors of the code.
Notable copyleft licenses include the GNU General Public License (GPL), originally written by Richard Stallman, which was the first software copyleft license to see extensive use, and the Creative Commons share-alike license condition, which is a copyleft license intended for other forms of intellectual property such as documents and pictures.
An early use of the word copyleft was in Li-Chen Wang's Palo Alto Tiny BASIC's distribution notice "@COPYLEFT ALL WRONGS RESERVED" in June 1976. Tiny BASIC was not distributed under any formal form of copyleft distribution terms, but it was presented in a context where source code was being shared and modified. In fact, Wang had earlier contributed edits to Tiny BASIC Extended before writing his own BASIC interpreter. He encouraged others to adapt his source code and publish their adaptions, as with Roger Rauskolb's version of PATB [Palo Alto Tiny BASIC] published in Interface Age [a magazine].
Rauskolb, Roger (December 1976). "Dr. Wang's Palo Alto Tiny BASIC". Interface Age. 2 (1): 92–108. (NB. The source code begins with the following nine lines: "TINY BASIC FOR INTEL 8080; VERSION 2.0; BY LI-CHEN WANG; MODIFIED AND TRANSLATED TO INTEL MNEMONICS; BY ROGER RAUSKOLB; 10 OCTOBER, 1976 ; @COPYLEFT; ALL WRONGS RESERVED")
- N.B. [Language: Latin; Origin: nota bene 'note well']
The concept of copyleft was described in Richard Stallman's GNU Manifesto in 1985, where he wrote:
GNU is not in the public domain. Everyone will be permitted to modify and redistribute GNU, but no distributor will be allowed to restrict its further redistribution. That is to say, proprietary modifications will not be allowed. I want to make sure that all versions of GNU remain free.
The copyleft symbol is a mirror image of the copyright symbol (C).
六级/考研单词: modify, intellect, derive, copyright, compute, hardware, patent, reciprocal, necessity, reproduce, author, notable, notify, edit, interpret, translate, domain, farther
标签：code,Tiny,copyleft,BASIC,was,software From： https://www.cnblogs.com/funwithwords/p/16619560.html