The continuation bet, or c-bet, is the first advanced poker strategy that most players learn, because it's almost impossible to sit through a poker game without seeing this trick used a great deal. A continuation bet takes place in a game of community poker (such as Texas Hold'em or Omaha) when a player makes a small raise before the flop and a larger one after the flop, regardless of whether or not the flop has improved his or her hand. This becomes a "continuation" of the previous bet-- thus giving this maneuver its name.
Why Make a Continuation Bet
There are a few reasons why you might want to make a c-bet. First and foremost, you don't want to let your opponents know if you didn't make the flop and are holding out for a draw or don't quite have the nuts. When used this way, the continuation bet is a bluff that is meant to give you some protection, as other players with hands of medium strength and those waiting for draws are more likely to fold, given that it seems like you now have something good in your hand. The problem that a lot of players run into is this: after first learning about continuation betting, they make a c-bet on every hand, which sends a clear message to your opponents that you're going to throw money into the pot after the flop, regardless of what comes down. This isn't a good way to play, and it negates all the good that the continuation bet can do. Some players, however, will use this methodology to trap their opponents, which brings us to the second big reason that you might be c-betting.
A continuation bet is also good for getting other players pot-committed when you have a very good chance of coming up with a draw (but the other players don't have as good as a chance at it). This is a sophisticated form of trapping, and it comes with certain risks, so it's not for the casual player or the light-hearted.
You might also make continuation bets to trick your opponents into thinking that you're c-betting on a future hand. If you make a series of c-bets early in the game, while the minimum bets are low, you can invest in building a reputation as someone who throws good money after a bad flop. This way, in later hands, you can bet post-flop when you have a good hand and the flop did help you, and other players will assume that you're bluffing and will be eager to call you. This is an excellent method of trapping other players (and like many trapping methods, it takes a while to create).
When Not to Continuation Bet
While continuation betting is an action that requires a lot of personal evaluation, there are some times when you definitely should not make a c-bet. C-bets are wildly profitable when used correctly, so avoid betting in these unfortunate circumstances, and you should do okay.
When you're getting predictable
If you c-bet too many hands in a row, people are going to start to get suspicious. Generally, this is something that you want to avoid. While waiting to trap other players when you finally get that great hand is a good tactic, it could be a while before that good hand comes, and if you're not in the opening stages of the game where the blinds are lower, you shouldn't waste your time trying to appear predictable so that you can take advantage of other players-- you'll likely end up shooting yourself in the foot.
When you're out of position
Continuation betting works best when you're in late position, because this gives you the opportunity to assess the status and hands of the other players at the table, letting you know whether their hands are strong enough to call you. If you try to c-bet from early position, you risk being met with multiple callers-- a definite sign that you should fold. Folding from a c-bet sends the clear message to your opponents of exactly what your strategy is, so it's best to avoid making c-bets that you're not going to be able to follow up on.
When you don't have the fold equity
Fold equity is one of the many mathematical terms that's a part of advanced poker strategy-- it's one of the things that professional players take into consideration while playing, which allows them to place bets and proceed through a game regardless of what hand they have, much like Annette Obrestad demonstrated when she won an online tournament, looking at her hand only once the entire time. Fold equity is basically the chance that an opponent will fold on a given pot and is used to calculate which move is the most profitable. Since the entire purpose of a c-bet is to get your opponent to fold, you need to know a bit about how each player plays. Likewise, if you have too many opponents who call your pre-flop raise, the fold equity goes down, because the more players you have, the less likely it is that they'll all fold. If you can't get everyone to fold, continuation betting runs the risk of getting you pot-committed against players with better hands.
When the board has high draw opportunity
If a player thinks that he has a good shot at nailing a draw, he probably won't fold. Since the entire purpose of a c-bet is to bluff and get yourself protection, getting other players to fold, if you're looking at a board that offers multiple opportunities for a flush or straight draw, it's not a good time for continuation betting. The last thing you want is to throw more money into a pot that you're not going to win. If the board comes down something like 10hQh9s, it's the kind of board that you're going to want to stay away from.
When the flop isn't promising... for anyone
If you're going to bluff your opponent and try to trick them into believing that you have a winning hand, there's no point in c-betting on a flop that's ultimately worthless for everyone. For instance, if the flop comes down 2h4s8d, it's not going to do anyone any favors. At best, a player might have a pair of eights (the nuts hand with this is trip eights, but it's highly unlikely that a player would raise with a pair of eights and then hit a third one on the flop), which is easily beatable. With a flop like this, you could also have a straight draw, but you definitely don't have a hand that's worth aggressive playing, and any opponent worth his or her salt is going to call your bluff.