Everyone likely understands what a bluff is in the game of poker. When you have a garbage hand and you want to represent that you have a strong hand, you fire at the pot, putting in enough money to make your deception convincing. If your bluff works, other players will lay down their hands, believing you have them beat. Showing a bluff is one of the more visceral joys in poker, especially No Limit Texas Hold'em when you can take huge risks and bluff all in. But there are two other kinds of bluffs in poker that deserve just as much attention, and if you learn how to use them properly, can win you a lot of hands.
The Semi Bluff
The semi bluff is when you make a bluff, but you actually have somewhat of a good hand. Betting with a middle pair in Texas Hold'em can be a semi bluff, especially if you bet big in No Limit or raise. Betting big on a draw is a form of semi bluff, because while you don't have anything now (the bluff part) you could if you catch a card down the road. Semi bluffs work because if the other players buy it and lay down the hand, you win something with a small hand, and if they don't, you could still win if you are lucky.
The Bluff Bluff
Sometimes you really want your opponent to think you are bluffing when in reality you have the best hand. When you have the Ace card plus another suited in a flush and three of the cards on the board finish it, you really, really want some callers. If you have been bluffing and caught early in the game, you can try to recreate the circumstances here and represent a bluff, when really you have the nut hand. If you manage to pull that off, it's payday.