It will happen often you find yourself in the situation where your hand needs to improve to end up winning. Every card that makes you the best hand, is called an out. Estimating this number of possible outs is thus a very important skill to master when playing poker. If you can calculate your outs, you know how big an underdog you are, and what pot odds you need to justify a call.
For example, consider this hand. You are in middle position before the flop and decide to raise with Queen and Ten of Hearts. An opponent in late position calls and the flop comes Ace spades, Jack Hearts and Eight Clubs.
You check, but your opponent doesnt. He bets. What are you supposed to do? At this moment, you dont have shit. But you have several outs to end up as the winner. Its at this point you have to calculate the possible cards that would save you. First point of notice is that your opponent could have a variety of hands. Your check on the flop showed weakness, so hit bet might be just an attempt to chase you off the hand with nothing. But off course he could have hit the flop. Lets review his possible holdings and see how many outs we have against each of them.
- He has a big hand
Its not so likely, but your opponent could have hit a real monster, like two pair or maybe a set. In this case you need a straight, or a running flush to win. We need a K or a 9 to hit our straight so that makes 8 outs (four kings and four nines left in the deck). The backdoor flush draw gives us 2 more outs (roughly estimated) so we have a total of ten outs. But if he really has a big hand some of these outs may be worthless. If he hit a set, every card that makes a pair on the board would make him a full house, so lets reduce our outs to max. 8 outs.
- He has a pair of aces
Mostly this would be the case. When I play over the internet, I see a lot of newbies call with any ace-x. They make the highest pair on the board and think they are good. Actually this result would be quite good. We still need to improve, but when we hit an out were quite certain to win the hand. Well have 10 full outs.
- He has a pair of jacks
This could be a possible holding too. I see a lot of people calling with KJ and KQ too. And since you showed weakness on the flop by checking, they want to win the hand as soon as possible and decide to start betting. In the case of a pair jacks, you see your amount of outs raise. Every queen (there are 3 left, since you hold one in your hand) will give you the winning hand. Our outs will be 10+3 = 13! Thats not a bad result.
- He has a lower pair
Maybe he has pocket nines or sevens and decided it was the right time to take down a winnable pot. In this case, every ten will be an out too, so it would give you 16 outs.