Card counting techniques are strategies used in blackjack to keep track of the ratio of high to low cards remaining in the deck, allowing players to make more informed betting decisions. One of the most popular methods is the Hi-Lo system, where players assign values to cards—high cards (10, face cards, and Aces) are given a negative value, low cards (2-6) a positive value, and cards 7-9 are neutral. As players tally these values, they adjust their bets based on the perceived advantage. Other techniques may involve more complex systems that assign different values to cards or use multiple decks, enhancing accuracy but also increasing difficulty.