Sometimes you know that your hand is just NOT a winning hand. You can surrender your hand and lose half your bet. But it is the first decision that you must make, before drawing a third card, splitting or making any other decision. Usually the dealer will check if he has Blackjack or not. Then you can decide whether it's a good idea to surrender.

Basic Surrender Strategy
Player's Hand	Dealer's Card
	9	10	A
15	N	Y	N
16	Y	Y	Y