Counting cards is a strategy used in the game of Blackjack to gain an advantage over the casino. Players keep track of the ratio of high to low cards remaining in the deck. By assigning values to cards—typically +1 for low cards (2-6) and -1 for high cards (10-A)—players can estimate the likelihood of favorable cards being dealt. This technique helps players make informed betting decisions. When the count is high, indicating more high cards are left, players may increase their bets. While counting cards is not illegal, casinos often discourage it and may ask players to leave if they suspect card counting.