Open content, coined by analogy with "open source," (though technically it is actually share-alike) describes any kind of creative work including articles, pictures, audio, and video that is published in a format that explicitly allows the copying of the information. Content can be either in the public domain or under a license like the GNU Free Documentation License. Wikipedia, Nupedia, and all Wikimedia projects are open content (see Wikipedia:Copyrights). "Open content" is also sometimes used to describe content that can be modified by anyone; there is no closed group like a commercial encyclopedia publisher responsible for all the editing.
It's possible that the first documented case of Open Content was with the Royal Society, where they aspired toward information sharing across the globe as a public enterprise. The commonality is difficult to dismiss.
Like the debate between the titles "open source" and "free software", open content materials can also be described as free content, although technically they describe different things. For example, the Open Directory is open content but is not free content. The main difference between licenses is the definition of freedom; some licenses attempt to maximize the freedom of all potential recipients in the future, while others maximize the freedom of the initial recipient.
Open content projects (in alphabetical order)
- Aozora Bunko - free digital Japanese books
- Asian Open Source Centre  - contains an open content GFDL wiki on open source 
- Authorama Public Domain Books - XHTML+CSS public domain books with Wiki-style annotation system for unregistered users
- BerliOS 
- Bitzi - free community-built catalog of digital files
- California Open Source Textbook Project  - K-12 textbooks and other curriculum materials
- Common Content  - open catalog of Creative Commons licensed content
- Connexions Repository  - Rice University's course material
- Creative Commons
- Eldritch Press  - books
- ExtinctionLevelEvent.com - Open Content Web Comic 
- Free High School Science Texts (FHSST) is a project to create free science textbooks to help reduce textbook costs especially in 3rd world and developing countries
- FreeMedia  - stock photos from the University of North Texas
- GrokDoc  - Usability study of GNU/Linux newbies
- Jake  - Research software and database where content is built in an open source way
- GNUtemberg  in Italian.
- ibiblio 
- Libre Society  - open culture site
- Linux documentation project  - Content project to develop documentation for Linux
- LOCA Records  - open content record label
- Magnatune  - open content record label
- Mediaweapon  - open content for the practise of political transparency in revolutionary theory
- Nupedia  - peer-reviewed encyclopedia
- Opart  - Open art pool
- Opencode  - consortium for open research and content
- OpenContent  - open source licensing scheme for information content
- Open Content for Education 
- Open Clip Art Library  - the open clip art library.
- Open-education.org  - Portal and advocacy-site for collaborative creation of Open Content Educational materials.
- Open Gaming Center - an open content experiment to create a games and gaming encyclopedia
- Openlaw  - Experiment in the open crafting of legal arguments
- Open-Songs - Free, Royalty Free MP3's
- Opsound  - Open sound pool, a record label.
- Open Directory Project  - web directory like Yahoo!.
- Open Music Registry  - Open sharing of music using an Open Audio License
- Open Photo  - stock photos
- OYEZ  - US Supreme Court multimedia
- Pickings.de (daily news review)
- Prelinger Archives  - government and advertising films
- Project Gutenberg 
- PlanetMath  - Math for the people, by the people.
- Sodipodi Clipart  - a large collection of flags of the world, and other clipart
- Wikimedia 
- Wikitravel  - travel guide (not part of Wikimedia)
- Woochi - Wine Encyclopaedia
- World66  - An open content travel guide
- World Lecture Hall  - Online course materials
- The Worldwide Lexicon
Related topics, not open content
- MIT OpenCourseWare  is not open-content material by the definition above, since copyrights remain with the Massachusetts Institute of Technology or members of its faculty.
- Creative Commons License (11 versions)
- Design Science License
- GNU Free Documentation License
- October Open Game License (OOGL) - deprecated: see Creative Commons Attribution-ShareAlike License
- Open Publication License - License for the Open Content Project
- Open Directory Project License used by Open Directory Project
- Open Game License - License of the Open Gaming Foundation , as drafted by Wizards of the Coast.
- Open Content License
public domain, free content, free software movement, open content movement, copyleft, open access, public domain resources, semi-public domain resources , public domain image resources, collaborative writing.
- alqua.com, Free documents
- Creative Commons - The open content idea and creative works
- Writings - Open Content - speech on Open Content with relation to DRM
- Design Science License
- ibiblio - The open content idea as a library
- Copyleft and the Information Renaissance
- locarecords.com, Open Source Record Label
- Jan Newmarch, "Open Content Licenses," http://jan.netcomp.monash.edu.au
- Open directory category: Open Content
- Open Content resources and mailing list at OpenContentList.com
- Public Library of Science
- Licenses for Documentation at gnu.org
- This Google search attempts to find documents with GFDL license grant boilerplate.
- Read Print - includes many free public domain books
The list of open content projects are partly based on The Institutional Design of Open Source Programming on Firstmonday