Quora is a question-and-answer site where questions are asked, answered, edited and organized by its community of users. Its publisher, Quora, Inc., is based in Mountain View, California. The company was founded in June 2009, and the website was made available to the public on June 21, 2010. Users can collaborate by editing questions and suggesting edits to other users' answers. Quora was co-founded by two former Facebook employees, Adam D'Angelo and Charlie Cheever. D'Angelo resigned from his position at Facebook in January 2010 to create Quora. He said that he and Cheever were inspired to create Quora because "we thought that Q & A is one of those areas on the internet where there are a lot of sites, but no one had come along and built something that was really good yet." Quoras base of users grew quickly[clarification needed] in December 2010.[unreliable source?] Quora had an estimated 500,000 registered users, as of January 2011. In June 2011, Quora redesigned its website, in order to make information discovery and navigation easier. Quora released an official iPhone app on September 29, 2011, followed by an Android app on September 5, 2012.