Outs
An out is a card still in the deck that would give you the best hand, and counting them is how you turn a draw into a number.
Count only the cards that actually win. With four hearts on the flop, nine hearts are left in the deck, so nine outs. Cards that improve you but still lose are not outs, which is why counting them honestly is the hard part.
From the flop there are 47 cards you have not seen. Nine outs means 9 in 47, or 19.1%, on the turn alone, and 35.0% with both cards to come. The often quoted shortcut of multiplying outs by four is close for nine outs and drifts too high as the number of outs grows.
an example
your cards
board
Four hearts are showing between your hand and the board, so nine remain. Those nine are your outs to the best flush. Eight outs would be an open ended straight draw at 31.5% by the river, and four outs a gutshot at 16.5%.
This example is made up. The real one is in your own hand history: find outs in your own hands and see how often it came up and what it cost you.
related terms
Equity
Your equity in a pot is the share of it you would win on average if the remaining cards were dealt out and nobody folded ...
Pot odds
Pot odds are the price you are offered on a call: what you have to put in compared with what the pot would be worth to y ...
Backdoor
A backdoor draw is one that needs both the turn and the river to complete, so on the flop it adds a little value to a ha ...
next
Knowing the word is not the same as seeing it.
Forty hands against a bot, no account, and your own hand history at the end.