Expected value (EV)
Also called EV
Expected value (EV) is the average result a poker decision would earn or lose if you made it over and over — the long-run profit or cost of a play in chips.
Every choice you make at the table has an expected value: take each possible outcome, weigh it by how often it happens, and add them up. A play with a positive EV makes chips on average over the long run, while a negative-EV play loses them. One hand can go either way, but the math is what plays out across thousands of similar spots.
It comes up most when you're deciding whether a call, bet, or fold is worth it. You compare what you can win against how often you'll win it, leaning on ideas like pot odds and equity. The goal isn't to win this particular hand, it's to keep choosing the option with the better long-run number.
For beginners, the comforting part is that you can make the best (highest-EV) decision and still lose the hand. That's normal and it's called variance. Judge yourself by whether your choices were profitable on average, not by whether the last river card was kind to you.
Example
You hold the 9-8 of hearts and the flop gives you two more hearts, so you have a flush draw: any of the 9 remaining hearts on the turn or river makes your flush. There are 4,000 chips in the pot and a bot bets 1,000, so it's 1,000 to call for a chance at a 5,000 pot — you only need to win about 1 time in 6 (roughly 17%) to break even. With two cards still to come you'll complete that flush around 35% of the time, well above what you need, so calling is the positive-EV play even though you'll still miss and lose the 1,000 plenty of the time.