This resource provides a basic overview guide to and links to repositories (content websites) that host creative commons and public domain content. There are several standard legal measures protecting ideas, content, and duplication of original works and ideas.
Intellectual Property (IP) laws protect ownership rights of an idea and created works. A subset law under the IP laws is defined to protect more specifically rights of ownership in relation to "the right to copy".
Copyright laws protect the rights holder (owner) by providing exclusive rights for copying, selling, and distributing a work or copies of a work. These rights were designed to be granted to the creator of a work and to only last for a limited time. Since the inception of copyright, rights holders may not necessarily the creator of the work but are credited with ownership. In addition, the limited time as always been expanded to include additional time.
In general *anything* created is protected by copyright. This protection is expressed in the Digital Millennium Copyright Act. Copyright extends to all content, both physical and digital. There are some exceptions to the default copyright protection. Any work produced before 1923 is considered by default to be public domain and by that meaning copyright free. This is probably one of the few understandable public domain exceptions in copyright law. Works created after 1923 could be under copyright. There is no set rule that the creator or copyright holder of a work needs to inform on the status of copyright. All works should be considered to be under copyright and for reuse permission from the creator or copyright holder should be sought. There are several alternative optional licenses for a creator or copyright hold to release a work under besides being under a copyright. Two of these are:
If a work is released under Public Domain then anyone is welcome to use the work for any purpose.
Typically these works will have a mention of being in public domain.
Creative Commons licenses are best explained by this video:
On the right side panel under Selected Resources are several links to web repositories that contain content either under a Creative Commons license or released as Public Domain. There are also methods of searching for these types of works. Creative Commons has provided a search engine to accomplish this task, CC Search.
There are other options for using content that is freely available with "All rights Reserved". This is discussed on the free use page. In addition a copyrighted work may be used in accordance with Fair Use or the TEACH Act.