When a player's cards value exceed the total of 21 points then his hand is "bust", meaning it's unplayable and a player automatically lose his bet. The blackjack busting odds vary according to the number of decks and the basic blackjack strategy relays on it.
Here are few examples of a "bust":
Eventually the main objective of blackjack is to avoid a bust; notice that when playing blackjack online you can find few blackjack variants where a hand of 22 points, which usually busts, is in fact playable, such as in Blackjack Switch, which you can be found at the online blackjack casinos.
Article contributed by Sam Marshall 27th of February '06