Casinos detect card counters using a mix of surveillance, dealer awareness, and tracking systems. Surveillance cameras monitor betting patterns and player behavior, looking for signs of irregular betting, such as large fluctuations after favorable cards are dealt. Dealers and pit bosses are trained to notice unusual behavior, like extreme focus or consistency in betting, which could suggest card counting. Additionally, casinos track player activity through comp programs and rewards cards, flagging sudden increases in bets or consistent wins. To limit counters' advantage, casinos may shuffle decks more often or use continuous shuffling machines. While card counting isn't illegal, casinos may ask suspected counters to leave or ban them if they believe they're gaining an edge.