A bluff is a move in where a player tries to make his opponents lay down their cards. It should make a player think that he is beaten and to make him lay down his cards. A bluff is a very important move for every poker player.
A lot of players still think that players make money from bluffing. The reality looks other. A good poker players bluffs maybe just 10-20% maximum, more realistic is even around 10%. The situation and the opponent must be the right. There exist different kind of bluffs. That can be a pure bluff with nothing and the change for nothing, or a semi bluff where you have at the moment no hand but there is the chance that you may complete a draw or straight if the right card will be dealt.