A three bet is a term used in both cash game and tournament play, and simply means to put in the third bet. The term is a little confusing to some players since it seems to imply putting in the third raise, when actually it generally refers to the second raise.
Confused? Here’s an example. Let’s say you are in the small blind. The table folds to the button, who raises. If you were to re-raise, you would be putting in the third bet. Why? Well, the button has actually put in two bets – his initial call and then his raise. When you make another raise, you’re putting a third bet into the pot.
Three betting is a critical part of modern poker. Before the advent of online poker, a third bet in no limit and pot limit games generally indicated a very strong hand. Now, as games have gotten more aggressive, the three bet is used quite liberally by players in cash and tournament play alike. Knowledge of when you should three bet and what your opponent’s three betting range is are both critical skills for players hoping to profit in modern poker.