Counting cards is a skill which is used by players of card games to achieve an advantage by tracking cards that have been used. This gives the player a notion of the value of cards, that have to be dealt with. Counting cards is an ability that has more use in blackjack than in any other card game.

In twenty-one, a gambler is at an advantage when the remaining shoe has "big value cards." High cards should be 10s or aces. The counter in the gambling hall takes advantage of these circumstances by laying larger wagers, as and when they occur. Many experienced gamblers use the makeup of the deck to change their overall course of action. New players on occasion experience problems while performing quick card counting and could be subject to errors, when it comes to working with dealt decks of cards. Chemin de fer card counting is a business on its own. Millions are made or squandered, both by the gamblers and the casinos, based on card counting strategies in play.

Technology has made its impact on counting cards too, with improved computing power impacting the entire activity. Old guard gamblers however vow that a more complex card counting approach is more subject to problems, canceling out the increased accuracy permitted by the use of computers. One can locate many tactics for 21 card counting by visiting net sites dedicated to the game. With the game growing in popularity in gambling dens all over the world, there are newer techniques being developed every other day. One can locate at least a multitude of internet sites providing you tricks on card counting and the all-around plan to make profit through vingt-et-un.