## Auto-converted by kwiki2moinmoin v2005-10-07
Copyleft describes a group of licenses applied to works such as software, documents, and art. Where copyright law is seen by the original proponents of copyleft as a way to restrict the right to make and redistribute copies of a particular work, a copyleft license uses copyright law in order to ensure that every person who receives a copy or derived version of a work, can use, modify, and also redistribute both the work, and derived versions of the work. Thus, in a non-legal sense, copyleft is the opposite of copyright.

See : 

 * [[GNU]]
 * [[GPL]]
 * [[GFDL]]
 * {Wikipedia:Copyleft}