The content models: Creative Commons
The birth of free content licenses
In earlier years, most of the content spread by the Net was (free and open-source) software. With Internet mainstreaming at the end of the 20th century, new network-based activities like telework and e-learning emerged and more and more non-software network content came into existence.
Freely usable materials were not new for Internet though. Since 1969, main technical questions concerning Internet internals were discussed in a special class of documents called Request For Comments (RFC). Project Gutenberg, a major online source of classical literature, started in 1971 and is active until today. Also there were growing quantities of fan fiction and other content. By the turn of the century, the network content has grown to the point where clearer legal status was started to be necessary.
In principle, the GNU GPL can also be used to license objects other than software, but the main problem is how to interpret the requirement to open the source code. In literature, we can think about the original manuscript as a form of source code (or in case a music, the original script of musical notation), but in case of a movie or a multimedia solution this is hazy at best.
In 1999, the Free Software Foundation introduced the Free Documentation License mostly meant for technical documentation and other writings, the idea was to carry the ideas that had already proved themselves successful in GPL over to other kinds of creative works. It found both support (the largest user of the FDL is probably Wikipedia) and criticism - the main issues raised were overtly ideological tone and ban of technical restrictions - well before the current controversy around the GPL v3 which prohibits the use of DRM and similar techniques, the FDL already prescribed these countermeasures. While the DRM is highly questionable by itself, more serious shortcomings found in the FDL were the "lawyer language" used, and also just the sheer volume of license text.
Another similar initiative was the Open Content Project launched by David Wiley in 1999. Its Open Publication License found limited use and did not achieve ubiquity (today, the creators of OPL recommend using either the FDL or CC licenses).
One more notable attempt was made by a group of French artists inspired by the GNU GPL - they tried to make something similar for works of art, creating the Free Art License. It has been used in limited scale until today. Just like the FDL, it will raise the question of "open source code" requirement - how to define the "source" in a painting, a sculpture or a piece of architecture?