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 April 2010, Alexa ranked as the 2,462nd most popular web site in the world. estimates that Wikibooks had 576,838 unique visitors, and Quantcast estimates unique visitors from the United States in that month.