Passive player - a player that prefers to check and call bets of opponents rather than make bets on himself. Passive player rarely takes the in-game initiative on himself (regardless of his hand strength). Such players very rarely make bets themselves, because they prefer to call bets of the opponents. Such player is more likely to adapt to his opponents style, then try to impose his own style of play.

Passive players are quite predictable, and by identifying this kind of player at your table, you would be able to use it for your own benefit.

It’s always a good idea to bet with a strong made hand against passive players, as well as to check hoping to improve your hand or to win the hand on a showdown with weak cards.

It’s important to understand, that if passive player decides to bet, in most cases he will have a very strong hand. You can easily fold a relatively strong hands in that case (strong top-pairs, two pairs, etc.).