Variance is a measure of uncertainty that determines how soon you can expect to win in a game of poker. When the game has high variance, your chances of winning the game become low. On the other hand, when the game variance is low, you are more certain about the outcome. Every time you fold, the variance becomes zero. A poker player should understand how variance works to keep realistic expectations from the game. It will also help you understand the notions of upswing and downswing. Players often lose their calm when they face a long downswing. Keep in mind that variance does not carry from one round to another and can last for a long time. It is better to take a break during the downswing to rebuild the bankroll.