Counting cards is a technique that is used by players of card games to gain an advantage by tracking cards that have been dealt. This gives the player a concept of the sum of cards, which have to be dealt with. Counting cards is a skill that has more use in twenty-one than in other card game.

In 21, a player has an advantage when the remaining deck houses "big value cards." High cards can be tens or aces. The counter in the casino brings into play such opportunities by making bigger bets, as and when they occur. Many skillful gamblers use the makeup of the deck to alter their overall tactic. New gamblers occasionally will have difficulty while engaged in fast card counting and could be prone to mistakes, when it comes to working with dealt cards. Twenty-one card counting is an enterprise by itself. Millions are won or spent, both by the gamblers and the gambling halls, based on card counting methods in play.

Technology has made its presence known on card counting too, with enhanced computing power impacting the complete activity. Traditional players however argue that a card counting plan of greater complexity is more prone to blunders, canceling out the increased accuracy enabled by the application of technology. Anyone can dig up many techniques for blackjack card counting by visiting online resources committed to the game. With the game growing in acceptance in gambling halls around the world, there are newer tactics coming up every other day. One can find at least thousands of Web sites providing you tricks on counting cards and the overall tactic to earn cash playing vingt-et-un.