Stud poker is any of a number of poker variants in which each player receives a mix of face-down and face-up cards dealt in multiple betting rounds. Stud games are also typically non-positional games, meaning that the player who bets first on each round may change from round to round (it is usually the player whose face-up cards make the best hand for the game being played). The cards dealt face down to each individual player are called hole cards (which gave rise to the common English expression ace in the hole, which suggests that one has something valuable that is not apparent to others).
The number of betting rounds in a game influences how well the game plays with different betting structures. Games with four or fewer betting rounds, such as five-card stud, play well with any structure, and are especially well suited to no limit and pot limit play. Games with more betting rounds are more suited to fixed limit or spread limit. It is common (and recommended) for later betting rounds to have higher limits than earlier ones. For example, a "$5/$10 Seven-card Stud" game in a Nevada casino allows $5 bets for the first two rounds and $10 bets for subsequent rounds. Also common is to make the final round even higher: a "$5/$10/$20" game would allow $20 bets on the last round only. Another common rule is to allow the larger bet on the second round if there is an "open pair" (that is, at least one player's upcards make a pair). Some casinos (typically in California) use the smaller limit on the first three rounds rather than just the first two.
It is a common convention in stud poker to name the betting rounds after the number of cards each player holds when that betting round begins. So the bet that occurs when each player has three cards is called "third card" or "third street", while the bet that occurs when each player has five cards is "fifth street". The final round, regardless of the number of betting rounds, is commonly called the "river" or simply the "end".