Online poker is the game of poker played over the Internet. It has been partly responsible for a huge increase in the number of poker players worldwide. Christiansen Capital Advisors stated online poker revenues grew from $82.7 million in 2001 to $2.4 billion in 2005, while a survey carried out by DrKW and Global Betting and Gaming Consultants asserted online poker revenues in 2004 were at $1.4 billion. In a testimony before the United States Senate regarding Internet Gaming, Grant Eve, a Certified Public Accountant representing the US Accounting Firm Joseph Eve, Certified Public Accountants, estimated that one in every four dollars gambled is gambled online.

Poker is a family of comparing card games in which players wager over which hand is best according to that specific game's rules. It is played worldwide, but in some places the rules may vary. While the earliest known form of the game was played with just 20 cards, today it is usually played with a standard deck, although in countries where short packs are common, it may be played with 32, 40 or 48 cards. Thus poker games vary in deck configuration, the number of cards in play, the number dealt face up or face down, and the number shared by all players, but all have rules that involve one or more rounds of betting.