A poker tell is something that a poker player unknowingly does that can be used to reveal information about his or her hand or strategy. All poker tells must be evaluated and interpreted – there is no poker tell “manual” to follow. It would of course be convenient if all our opponents held their cards closer to their body when they had a strong hand and scratch their face when they were bluffing, but this simply isn't the case. Also, a skilled poker player may use well established poker tell myths to deliberately fool less cunning opponents at his table.
In movies and TV-series, poker tells are often depicted as strictly physical “tics”. A player touches her necklace when she's bluffing or get's dilated pupils when the right card lands on the table. In reality, poker tells may just as well be non-physical things, such as how much time you need to think before making a bet. This is why poker tells exist online as well as offline.
One example of a poker tell that can be noticed online as well as offline is sudden deviations from an established betting pattern. If a player who is known to bet conservatively all of a sudden makes a large bet from a bad position, experienced players at the table will notice and try to interpret this alternation. The same is true if a player that normally needs to ponder every decision for ages suddenly takes once quick glance at her cards before acting. Of course, if you know that you have fairly skilled and attentive poker players at your table you may try to trick them by intentionally using these perceived tells after establishing your betting pattern. If you on the other hand are playing with novices that are too focused on their own hands to pay any attention to you, trying to trick them with overly elaborate schemes is usually a bad idea.
Since poker tells are a change in behavior, they will be easier to notice and interpret if you pay attention to your fellow players. When playing online you can even take notes to help your memory. Paying attention to everything that goes on around you might be tiring at first, but as you become a more experienced poker player you will start doing it more or less automatically and also become better at sifting and processing large amounts of information. Fore some poker players, this new skill will even transfer over to other parts of their lives and they will start noticing and taking advantage of miniscule pieces of information that they would not even have seen earlier.
While paying attention to your opponents it is equally important to pay attention to yourself. Which are your tells? What type of information are you sending out? Which type of persona do you wish to project at the poker table? Don't be too proud to acknowledge that you may have tells too. If you have poker playing friends, you can help each other out by playing together and point out each other's poker tells and other types of behavior at the table that the player might be unaware of. Just like discussing poker hands and betting choices with friends can make you a better player, discussing poker tells can make you a better player and give you that extra edge at the table.