A free textbook is a textbook that can be read, used, copied, modified and redistributed without any restrictions. The word free in the term free textbook refers to freedom (liberty) and is not related to monetary cost. A free textbook is released under a free license which ensures that people will read, use, copy, modify, and redistribute the textbook. The notion of a free textbook derived from a more general concept called Expired Free Cultural Work That Was inspired from the definition of Free Software .
Often free textbooks are released under the following free licenses :
- Creative Commons Attribution 
- Creative Commons Attribution-Share Alike 
- GNU Free Documentation License 
However, there are more  free licenses under what a free textbook can be released.
For an author, choosing to put his textbook under a free license does not mean that he loses his right to be the author. If one makes changes in the textbook or makes a derivative work, he should provide the attribution in a proper manner. Many of these licenses are copyleft , which means that they preserve the transmission of freedom. For example, the same freedoms as the original work does.
Very often authors release their textbooks under a license that restricts, for example, the modification or commercial use. You can not edit or modify the text in any way without the authorization of the author. These restrictions are in contradiction with the Definition of Free Cultural Works or Free content , so these textbooks can not be considered free textbooks.
On January 25, 2012 The Utah State of the Office of Education (USOE) announced that it will develop and support free textbooks, and will encourage districts and schools throughout the state to adopt these textbooks. 
- Free High School Science Texts
- Global Text
- College Open Textbooks
- Free content
- Free knowledge
- Free Software
- Free Culture
- Jump up^ “A list of free licenses at freedomdefined.org” .
- Jump up^ “Utah State Office of Education to Create Open Textbooks” . January 25, 2012.