A tell is a physical action that sometimes or inadvertently indicates what a player is going to do or what cards he/she is holding. Extreme examples would be folding out of turn (the ultimate and really easy to spot!) or betting/raising out of turn indicating excitement. However, there are lots in between. Advanced players/pros also look for betting patterns. An easy one is when tight player suddenly bets the pot, goes all in, or re-raises. Can you tell a tell?