Open
The act of making the first non-zero bet in a betting round is called opening the round. On the first betting round, it is also called opening the pot. Some games may have special rules about opening a round that may not apply to other bets. For example, they may have a betting structure that specifies different allowable amounts for opening than for other bets, or they may require a player to hold certain cards to open.

Call
To call is to make the total amount of one's bet equal to the amount of the immediately preceding bet (which will be the largest bet made in that round). All players must eventually call an equal amount for the betting round to end, or else one player must bet an amount that no one calls, thus ending the entire deal and awarding him the pot.

The second and subsequent calls of a particular bet amount are sometimes called overcalls.

A player calling a raise before he or she has invested money in the pot in that round is cold calling. For example, if in a betting round, Jerry bets, Sally raises, and Eric calls, Eric "calls two bets cold".

A player calling instead of raising with a strong hand is smooth calling, a form of slowplay. Smooth calling is generally done in early betting rounds and against only one or two opponents; otherwise at least one opponent may have too good a chance of drawing out on the smooth caller and the trap backfires.

In public card rooms and casinos where verbal declarations are binding, the word "call" is such a declaration. In particular, the practice commonly seen in poker games on television and in movies of saying "I call, and raise $100" is considered a string raise and is not allowed in a serious poker game. Saying "I call" commits you to the action of calling, and only calling.

Check
When no one has yet opened the betting round, one may check, which is equivalent to calling the current bet of zero. The player declines making a bet; indicating that he does not choose to open, but that he wishes to keep his cards and retain the right to call or raise later in the same round if some other player opens. A common way to signify checking is to tap the table with a fist or an open hand.

A player with a live blind who chooses not to take advantage of his right to raise is said to check his option, which can be signified the same way.

Raise
To raise is to make the amount of one's bet greater than the amount of the immediately preceding bet, forcing all subsequent players to call the new amount. If the current bet amount is nothing, this action is considered the opening bet. A player making the second (not counting the open) or subsequent raise of a betting round is often said to reraise.

Except in the case of a live blind, a player may not raise the current bet amount if he is the one who first set it. If it is that player's turn to act who first set the current amount, the betting round is closed and no further betting may take place in this round. This occurs when all other players have either called the amount or folded. All remaining players will have bet an equal total amount (except for some rare cases covered by table stakes rules).

A universal rule in casinos in the United States, and common in home games as well, is that any raise must at least equal the amount of the previous raise. For example, if a player in a spread limit or no limit game bets $5, the next player may raise by another $5 or more, but he may not raise by only $2, even if that would otherwise conform to the game's betting structure. The primary purpose of this rule is to avoid game delays caused by "nuisance" raises (small raises of large bets that do not affect the bet amount much but that take time). This rule is often overridden by table stakes rules, so that a player may in fact raise a $5 bet by $2 if that $2 is his entire remaining stake.

In many casinos, for fixed-limit or spread-limit games, there is a limit to the total number of raises allowed in a single betting round (typically three or four, not including the opening bet of a round). For example in a casino with a three-raise rule, if one player opens the betting for $5, the next raises by $5 making it $10, a third player raises another $5, and a fourth player raises $5 again making the current bet $20, the betting is said to be capped at that point, and no further raises beyond the $20 level will be allowed on that round. It is common to suspend this rule when there are only two players betting in the round (called being heads-up). Pot-limit and no-limit games do not have a limit on the number of raises.