PokerStars is the largest online poker cardroom in the world.

PokerStars' satellite tournaments produced the 2003 World Series of Poker champion, Chris Moneymaker, as well as the 2004 champion, Greg "Fossilman" Raymer. Those two now act as spokespeople for the cardroom, as does 2005 World Series of Poker champion Joe Hachem, also a regular player on the site. In March 2007, poker room manager Lee Jones announced his retirement, effective April 1. His successor has yet to be named.

Launched in September 2001, PokerStars was originally a Costa Rican company, Rational Enterprises, majority owned by the Scheinberg family of Israel. The company was subsequently moved to the Isle of Man, a British Crown dependency. The move was driven by the establishment of a 0% corporate tax rate, and the removal of rules barring companies from accepting casino and poker bets from America, where internet gambling is illegal. PokerStars holds its license with the Isle of Man Gambling Supervision Commission. Since relocating, PokerStars has been the subject of financial media speculation regarding a possible initial public offering or merger with a publicly listed company. Analysts estimate its market value would be approximately $2 billion (US), which would make the company one of the world's largest privately held gambling companies.

PokerStars overtook PartyPoker as the world's largest online poker room at around the time the U.S. Congress passed the Unlawful Internet Gambling Enforcement Act. Many sites, including PartyPoker, immediately suspended business with U.S. gamblers, while others, including PokerStars, did not. On May 19, 2007, PokerStars dealt their 10 billionth hand.

Since then Pokerstars has grown and has roughly 120,000 players at their tables on a consistent basis and continues to grow at a steady pace.

PokerStars is the headline sponsor of the European Poker Tour. PokerStars sponsored an event on the World Poker Tour called the PokerStars Caribbean Poker Adventure. The World Poker Tour no longer stages this event, so it is now a stop on the European Poker Tour. In 2005, eGaming Review named PokerStars.com the "Best Poker Operator of the Year".

PokerStars offers eight varieties of poker games: Texas hold 'em, Omaha, Omaha Hi/Lo (8 or Better), Stud, Stud Hi/Lo (8 or Better), Razz, five-card draw, and deuce to seven triple draw. HORSE and HOSE, "mixed games" that rotate through several of the above, are also offered. Players can participate in real money games ranging from $.01/$.02 (micro limits) up to $1000/$2000.

Pokerstars offers hand history files for analysis, discussion and conversion using a poker hand converter.

The home of the World Championship of Online Poker, the largest online poker tournament series in the world, PokerStars has over 20,000 players playing real money ring games daily, plus thousands more playing real money tournaments or free-play games. During peak operating times, this often adds up to over 150,000 players online simultaneously. PokerStars.com's play money players mix with those logging in from PokerStars.net, a free play-only site without real money games.