Wikibooks (previously called "Wikimedia Free Textbook Project" and "Wikimedia-Textbooks") is a wiki-based Wikimedia project hosted by the Wikimedia Foundation for the creation of free content textbooks and annotated texts that anyone can edit. 

In June 2016, Compete.com estimated that Wikibooks had 1,478,812 unique visitors. 

The wikibooks.org domain was registered on . It was launched to host and build free textbooks on subjects such as organic chemistry and physics. There are two major sub-projects, Wikijunior and Wikiversity, were created within Wikibooks before its official policy was later changed so that future incubator type projects are started according to the Wikimedia Foundation's new project policy. 

In August 2006, Wikiversity became an independent Wikimedia Foundation project. 

Since 2008, Wikibooks is included in BASE 

Wikijunior is a subproject of Wikibooks that specializes in books for children. The project consists of both a magazine and a website, and is currently being developed in English, Danish, Finnish, French, German, Italian, Japanese, Spanish and Arabic. It is funded by a grant from the Beck Foundation. 

While some books are original, others began as text copied over from other sources of free content textbooks found on the Internet. All of the site's content is released under a Creative Commons Attribution-Share Alike license (or a compatible license). This means that, as with its sister project, Wikipedia, contributions remain copyrighted to their creators, while the licensing ensures that it can be freely distributed and reused subject to certain conditions.
What is wikibooks?
Wikibooks (previously called "Wikimedia Free Textbook Project" and "Wikimedia-Textbooks") is a wiki-based Wikimedia project 