Card counting is a technique used by some blackjack players to gain an advantage over the casino. It involves keeping track of the cards that have been played in a game, in order to determine when the deck is favorable to the player. While it is not illegal, most casinos view card counting as cheating and will take steps to prevent it.

There are several ways that casinos can catch card counters. One of the most common methods is through the use of surveillance cameras, which can be used to monitor players and look for suspicious behavior. Casino staff are also trained to watch for signs of card counting, such as players who are keeping track of the cards or betting unusually large amounts at certain times.

Another way that casinos can catch card counters is by using software that can track the cards that have been played and identify patterns that may indicate card counting. This software can be integrated with surveillance cameras and other systems to automatically alert casino staff when a potential card counter is detected.

Overall, casinos have a range of tools and techniques at their disposal to catch card counters and prevent them from gaining an unfair advantage. While it is not always possible to catch every card counter, most casinos are able to effectively identify and deal with this type of behavior.