World Series of Poker

The World Series of Poker (WSOP) is a series of poker tournaments held annually in Las Vegas and, since 2005, sponsored by Caesars Entertainment (known as Harrah's Entertainment until 2010). It dates its origins to 1970, when Benny Binion invited seven 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.