Counting cards is an ability that is used by players of card games to achieve an opportunity by tracking cards that have been used. This gives the gambler a concept of the value of cards, which need to be dealt with. Card counting is a technique that has more use in black jack than in any other card game.

In vingt-et-un, a gambler is at an advantage when the remaining shoe contains "big value cards." High cards could be faces or aces. The counter in the gambling hall brings into play such opportunities by making bigger bets, as and when they happen. Many skillful players use the composition of the shoe to change their overall tactic. Inexperienced players on occasion experience problems while engaged in fast card counting and could be subject to mistakes, when it comes to working with dealt cards. Chemin de fer card counting is an industry on its own. Millions are won or spent, by both the gamblers and the gambling halls, depending on card counting strategies in use.

Computing has made its presence known on counting cards too, with improved devices affecting the entire process. Traditional players however attest that a more complicated card counting system is more prone to breakdown, negating the added accuracy enabled by the application of computers. Anyone can find a lot of techniques for 21 card counting by going internet resources dedicated to the game. With the game increasing in appeal in gambling dens around the globe, there are newer strategies being created every other day. One can locate easily thousands of internet sites giving you ways on counting cards and the all-around strategy to earn money playing 21.