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, redistribute, and produce modified versions of and works derived from 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 the law 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 easily become non-free again with all its derivatives becoming non-free or illegal, if the copyright law changes.

Traditional Copyright

main: Copyright

Traditionally, copyright is a legal concept, which grants the author or creator of a work, legal rights to control the distribution and display of their work, in many jurisdicitons this is limited by a time period after which the works then enter the public domain. During the time period of copyright the author's work may only be distributed, displayed or modified with the consent of the author, usually via a copyright licence.

From the perspective of free content, traditional usages of copyright is limiting in several ways. It limits the distribution of the work of the author to those who can, or are willing to, afford the payment of royalties to the author for usage of the authors content. Secondly it creates a perceived barrier between authors, which limits modification of the work, such as in the form of mashups and collaborative content.

Public Domain

main: Public domain

The public domain is a range of abstract materials – commonly referred to as intellectual property – which are not owned or controlled by anyone. A public domain work is a work whose author has either relinquished, or no longer can claim control over the distribution and usage of the work. As such any person may manipulate, distribute or otherwise utilise the work, without legal ramifications. A work released as public domain by its author is free and copycenter.

Copyleft

main: Copyleft

Copyleft is a play on the word copyright and describes the practice of using copyright law to remove restrictions on distributing copies and modified versions of a work. The aim of copyleft is to use the legal framework of copyright to enable non-author parties to be able to reuse and, in many licencing schemes, modify content that is created by an author. Unlike public domain work, the author still maintains copyright over the material, however the author has granted a non-exclusive licence to any person to distribute, and often modify, the work. Some copyleft licenses require that any derivative works be distributed under the same terms, and that the original copyright notices be maintained.