If you watch a lot of poker on television, you've probably noticed how most no-limit hold'em hands are contested heads-up after the flop. A player opens with a raise, another calls, then it's just the two of them battling for the pot thereafter.
The same is true if you happen to rail online poker games involving better poker players, such as the big weekly tournaments and Sunday majors. Unlike perhaps is the case in many home games and also lower-limit live games, there's often going to be just two players left by the time the community cards arrive.