Early American poker was played with just twenty cards on river steamboats
The poker an English actor watched on a steamboat in 1829 used a pack of only twenty cards, ranked from ace at the top down to ten. Gambling riverboats on the Mississippi and around New Orleans spread the game through the American South in the 1830s.
Where poker came from is argued over. Scholars often cite the French game Poque and the Persian game As-Nas as possible inspirations, and in the 1937 Foster's Complete Hoyle, R. F. Foster declared the early twenty-card American game to be As-Nas without doubt. From the 1990s historians including David Parlett challenged that direct descent. The eyewitness account of the 1829 steamboat game comes from the actor Joe Cowell.
Other variants came later. Seven-card stud emerged in the mid-19th century, carried widely by the US military, became a casino standard after World War II and got another lift once the World Series of Poker began in the 1970s. After that, Texas hold 'em and other games with shared community cards then took over. Television coverage around the turn of the millennium fed a boom between 2003 and 2006, and in the 21st century poker moved from small circles of enthusiasts to a mass pastime with online play, professional players, big audiences and tournament prizes worth millions.
Today most games use a standard 52-card deck, though regions favouring short packs play with 32, 40 or 48. Variants differ in how many cards are dealt, how many are face up or shared, but all involve rounds of betting. Play usually opens with forced bets called blinds or antes. Moving clockwise, each player must call the highest bet so far, raise it, or fold and forfeit what they have put in. If everyone but one player folds, that player takes the pot without showing a hand; otherwise the survivors reveal their cards at a showdown.
Apart from the forced bets, nobody has to put money in. Chips go into the pot only when a player thinks the wager is profitable on average or wants to bluff opponents into folding. Any single hand turns heavily on luck, but over many hands results depend on decisions grounded in probability, psychology and game theory.
Source: Poker
