Choice of license
A copyright license can take many forms. Copyright, as a concept, is related to rights in general and to property rights in particular. Property rights are about social organisation: how can people related to each other and through the objects that surround them? Property is not referring to objects as such, but should be understood as some sort of articulation that makes it possible for people to live together without too much friction. Property rights such as those used in the Liberal/capitalist market economy are based on exclusion: if this is my car it is my right to exclude you from using it (and a whole range of other stipulations and restrictions, as well as permissions are possible for the proprietor). The genius of the basic Free Software document, which is in effect the constitution of the Free Softwqare community, the GNU General Public Licence (or simply the GPL), is that is subverts the exclusionary logic and bases its property rights around distribution instead. That is the concept of Copyleft. Copyleft is a particular Copyright. It is radically different, but it is a Copyright, since it deals with issues that a creator or inventor may have with her work.