Bluffing is betting or raising with an inferior hand. By bluffing you will make your opponents think you have a dominant hand, so that they all fold theirs.
In some circumstances bluffing can be more effective than others. The profitability of the bluff grows if the probability of being called decreases. The following circumstances are indications for bluffing:
If a player bluffs rarely, observant opponents will recognize that the player is value-betting and will only call with very strong hands or with drawing hands when the pot odds are favourable. If a player bluffs too frequently, observant opponents snap-off his bluffs by calling or reraising. Occasional bluffing disguises not just the hands a player is bluffing with, but also his legitimate hands that opponents may think he may be bluffing with. David Sklansky, in his book The Theory of Poker, states "Mathematically, the optimal bluffing strategy is to bluff in such a way that the chances against your bluffing are identical to the pot odds your opponent is getting."
Optimal bluffing also requires that the bluffs must be performed in such a manner that opponents cannot tell when a player is bluffing or not. Prevent predictable patterns in your bluffs by using a randomizing agent to determine whether to bluff. For example, use the colors of your hidden cards, the second hand on your watch, or any other unpredictable factor to determine whether to bluff.
A special type of bluff is the semi-bluff
which is a bluff with an inferior or drawing hand that might improve in a later round.