Definition
Live tells (or "reads") are physical, behavioral, or timing-based cues that convey information about an opponent's hand strength. Reading opponents accurately is one of poker's most celebrated skills — exemplified by players like Phil Ivey, Daniel Negreanu, and Phil Hellmuth who have built reputations for "supernatural" ability to read hands.
Common categories of tells: strength tells (opponents with strong hands may act weak, and vice versa), timing tells (instant bets often indicate strong hands or pre-decided bluffs; long pauses before betting suggest genuine decisions), and physical tells (breathing, posture, eye contact, chip handling patterns).
In online poker, reads are replaced by timing and betting pattern analysis. While less theatrical than live tells, online timing tells can be equally informative — players often take longer on difficult decisions and act quickly in auto-pilot situations.
The most reliable reads come from patterns observed over many hands with a specific opponent, rather than from single-hand observations.
Example
You notice that an opponent always checks back the turn when they have a medium-strength made hand but never when they have a strong hand or complete air. On a later hand, their turn check signals a medium holding — you can exploit this pattern by betting the river frequently, knowing they often have hands they'll fold.