Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. The World Series of Poker (WSOP) is a world-renowned series of poker tournaments held annually in Las Vegas and, since 2005, sponsored by Harrah''s Entertainment. It dates its origins to 1970, when Benny Binion invited six of the best-known poker players to the Horseshoe Casino for a single tournament, with a set start and stop time, and a winner determined by secret ballot.