The chance of winning if all the cards are run out.
It is also your share of the pot. For draws you get it from outs; preflop, against the opponent's range. Example. AA vs KK is about 82%, AKs vs QQ about 46% (AKo about 43%). In Hi-Lo games (Omaha Hi-Lo, Stud 8), count your share of the pot (including halves and quarters), not your chance of winning.