Understanding and calculating pot odds is an integral part of poker. If you aren't figuring out how to make the most money then you're really just gambling and hoping.

Calculating pot odds is a fairly simple process.

Compare the total number of unknown cards to how many outs you have and then divide.

For example, if you are four to a flush (IE: you have the Ace of hearts and Ten of hearts in your hand and the board has two hearts after the turn) there are 46 cards that are unknown. There are 52 cards total you know your two cards and there are four community cards. Out of 46 unknown cards, 9 of them have the same suit as your heart flush draw. 37 cards do not help you but 9 do. The odds are 37/9 or 4.1:1 against you making your nut flush.

The profitable play is to only call if there's already 4 times the amount already in the pot. In a $5/$10 game there needs to be at least $40 in the pot already to call a $10 bet and see the river. If your opponent bets more than $10 you would not have the correct odds to make a profitable call in the long run.