Introduction
Someone asked for an introduction to position. Here it is, short and sweet.
In poker, position refers to the order in which the players act. Acting later in the hand gives you an advantage. Here we're going to look at why that is and some of the more basic ways you can leverage position in my standard example-heavy format. Note that IP means "in position" or acting last, and OOP means "out of position" or not acting last.
On the Existence of the Positional Advantage
Consider the following. In the book The Mathematics of Poker by Bill Chen and Jerrod Ankenman, the authors investigate a number of simplified heads-up poker games. Most (if not all) of these games pit one player out of position against another player who is in position while they both have the same range. In all of these games, the player who is in position has an advantage. I say this first because I want you to realize that even in the simplest forms of poker (like the fixed-limit AKQ games or heads-up no-limit push/fold games), position gives you a sizable advantage. So in a game as complicated as no-limit hold'em, position will give you an advantage as well.
The Basic Advantage: Difference in Information
Suppose you're heads-up on some street of poker and you're in position. When it's your first turn to act on that street, you will know your opponent's first action on that street. When it's your opponent's first turn to act on that street, they will not know your first action. This diffence in information gives you an advantage. This advantage occurs every street that you play in position.
Ending the Street
If it checks to you IP and you check, that ends the betting street. If you're OOP and check, that doesn't end the street. This means that the player IP has more opportunities for things like free card plays with draws, or taking medium-strength hands one more step towards a showdown. This leads to having more options, which means an advantage.
Controlling the Betting: Playing the Worst Hand and the Best Hand
Suppose you're in position heads-up on the river. Your opponent bets, you call, and you lose at showdown. Now suppose you were out of position instead. Sometimes you would bet instead of checking, and your opponent would raise you instead of calling, and sometimes you'd call instead of folding. This means that on average you're going to lose less when you have the worst hand when you're IP.
Suppose you're out of position heads-up on the river. You bet, your opponent calls, and you win at showdown. Now suppose you were in position instead. Sometimes your opponent would bet instead of checking, and you would raise instead of calling, and sometimes your opponent would call instead of folding. This means that on average you're going to win more when you have the best hand when you're IP.
Facing Stronger Ranges: A Pre-Flop Example
We often call pre-flop in position with hands that are behind our opponent's opening range. For example, when 100bb deep, if our opponent opens to 3x with about 5% of hands (roughly {99+,AJs+,KQs,AKo} according to PokerStove), and we call this raise with 76s on the button, we only have about 30% equity. If we were all-in pre-flop, this would be a big mistake. But we're not all-in pre-flop. Now our opponent has to play out of position against us for three streets. The positional advantage and the hand strength advantage are at odds here.
Putting it All Together
Position is one of the three major areas where we can get an advantage. The other two areas are the strength of our range and our playing ability. Of the three, it's the one that's probably the least understood among beginning players, so get to understanding it. Good luck.
