Library : Free and open content

Open content, a neologism coined by analogy with "open source", describes any kind of creative work, or content, published under a license that explicitly allows copying and modifying of its information by anyone, not exclusively by a closed organization, firm or individual. Open content is an alternative paradigm to the use of copyright to create monopolies; rather than leading to monopoly, open content facilitates the democratization of knowledge.
The term "open content" has an ambiguity. It means that anyone can get copies of the content (e.g. source code) but it can also mean that it gives the user certain copyright freedoms.
The largest open content project is Wikipedia.
Free content, or free information, is any kind of functional work, artwork, or other creative content having no significant legal restriction relative to people's freedom to use, distribute copies, modify, and to distribute derived works of the content. It is distinct from open content in that it can be modified, whereas one might not have that ability with content that is simply "open" and not "free".
Free content encompasses all works in the public domain and also those copyrighted works whose licenses honor and uphold the freedoms mentioned above. Because copyright law in most countries by default grants copyright holders monopolistic control over their creations, copyrighted content must be explicitly declared free, usually by the referencing or inclusion of licensing statements from within the work.
Though a work which is in the public domain because its copyright has expired is considered free, it can become non-free again with all its derivatives becoming non-free or illegal, if the copyright law changes.