In standard casino games like blackjack, you play strictly against a cold, mathematical algorithm or a heavily regulated dealer following rigid rules.

These physical and behavioral leaks are known universally in the poker world as "tells."
Spotting Nervousness and Comfort
The human body is incredibly terrible at hiding massive spikes in adrenaline caused by extreme stress or intense excitement.

Conversely, a player holding absolute garbage cards will generally appear relaxed, bored, or artificially focused on an irrelevant distraction.
Physical tells are involuntary physiological reactions to extreme stress or excitementTrembling hands when betting usually indicates a massive, unbeatable monster handA rapid, pulsing vein in the neck is a clear, uncontrollable sign of a massive adrenaline rush Why Sizing Reveals Everything
While physical twitches are dramatic and fun to spot, the absolute most reliable tell in all of poker is a player's actual betting pattern.

Furthermore, timing tells are incredibly accurate, especially in the fast-paced environment of online poker.
The Danger of Reverse Tells
You must actively observe how a player acts when they are entirely relaxed and not involved in a hand to create an accurate behavioral baseline.

Furthermore, as you move up in stakes, you will encounter highly skilled professionals who actively broadcast "reverse tells."
Online Timing TellInterpretationInsta-Check on the FlopWeakness, giving up on the handLong tank, then minimum betTrying to induce a bluff raise
Spend your time at the table actively studying your opponents rather than staring mindlessly at your phone between hands.