“Related to the public domain is the more general idea of “the commons”—resources that are not divided into individual bits of property but rather are jointly held so that anyone may use them without special permission. Think of public streets, parks, waterways, outer space, and creative works in the public domain—all of these things are, in a way, part of the commons.
The “tragedy of the commons” is the familiar notion that widespread public use of a commons leads to its inevitable depletion. But some resources, once created, cannot be depleted. In the words of Thomas Jefferson, “He who receives an idea from me, receives instruction himself without lessening mine; as he who lights his taper at mine receives light without darkening me.” An idea is not diminished when more people use it. Creative Commons aspires to cultivate a commons in which people can feel free to reuse not only ideas, but also words, images, and music without asking permission—because permission has already been granted to everyone.”