Blackjack (also known as Twenty-one, Vingt-et-un (French for Twenty-one), or Pontoon) is one of the most popular casino games in the world. Much of blackjack's popularity is due to the mix of chance with elements of skill, and the publicity that surrounds card counting (calculating the probability of advantages based on the ratio of high cards to low cards). The casino version of the game should not be confused with the British card game Black Jack.