A Tell is a telltale sign of a player that allows an opponent who notices the Tell to draw conclusions about the style of play or the hand of the player. A distinction is made between conscious and unconscious tells, in tells of players who act and know or believe that they are being watched, and in tells of players who feel unobserved.
The way a player pushes the chips into the middle in a live game can be a tell. The Weak-Means-Strong-Tell, which occurs when a player tends to play a strong hand, always weak and a weak hand or a bluff always strong, is also well-known and widely used among beginners. Some players have the habit of always looking to the left in an all-in bluff. That too is a tell. Another group is called timing tells, which allows a player to disclose information about their hand by taking a certain amount of time to complete an action. The bandwidth is very big.