Well, Pot Odds is the ratio of what is already in the pot to the amount you would have to bet to stay in the hand. So, if there are $36 in the pot, and you would need to bet $6 to stay in the hand, the pot odds are 36 to 6, or 6 to 1.
Why would you need to know this?
One example of using pot odds is when your hand is not yet the best hand at the table, but it could be if the right card comes up next. For instance, with four cards on the board you hold four clubs. The odds of completing the flush on the river are roughly 5 to 1 against you. That means for you to bet there should be at least five times the bet amount in the pot. If the bet to you is $2, then there should be at least $10 in the pot to make it worth calling.
Suppose there were $24 in the pot when you were making that decision. The odds of landing that club and getting the best hand at the table were 5 to 1. The pot would pay you 12 to 1 on your bet. That makes calling the bet the right decision to make. You may not land your club and win the hand, but over the long run playing this way will be to your advantage.
Another instance of using pot odds is after the river, when the final bet comes to you. If the pot holds $40, and the bet in front of you is $4, you can use pot odds to decide what to do. The pot is laying you Ten to One odds. ($40 against your $4 bet). Even though you feel your opponent may have the better hand, do you think he is ten times more likely to have a better hand? If so, fold. If not, call the bet and see his cards.
There are plenty of times at the poker table when you will be asking yourself, "Is it worth staying in this hand?". Being able to use pot odds will help you answer that question correctly more often.
this article compliments of the Poker Prophet.