Blackjack, also known as twenty-one and pontoon in British English , is one of the most popular casino card games in the world. Its precursor was "vingt-et-un" which originated in French casinos around 1700, and which did not offer the 3:2 bonus for a two-card 21. Much of blackjack's popularity is due to the mix of chance with elements of skill and decision making, and the publicity that surrounds the practice of card counting, a skill with which players can turn the odds of the game in their favor by making betting decisions based on the values of the cards known to remain in the deck.