In poker, position refers to the sequence in which players may act. A player who acts early is said to be "out of position," while a player who acts last is "in position." In most circumstances, the dealer defines your position.
Here is a brief overview of why playing in position is crucial in poker.
Bluffing opportunities
Position against an opponent is so significant that it may often compensate for a relatively poor hand.
Being the last to act allows you to apply significant pressure while appearing to have a better hand when your opponent, who is out of position, shows weakness by checking.
Even if your hand strength is modest, acting last gives you far more leverage when attempting to represent better poker hands. The more your opponent checks on you when you are in position, the more opportunities you have to bluff.
See your opponents action
You learn about your opponent's hand strength when you are in position. They are likely to be weak if they check or make small bets. We may alter our strategy accordingly.
On the other hand, the out-of-position player is unaware of our hand strength. If they knew if we intended to bet or check, they could make a better-informed decision.
Most good players utilize an opponent's action as a core element when selecting how to play each street while in position.
Pot control
Acting last on every post-flop round often allows you to control the size of the pot you play. If you want to play in a small pot and a player checks, you have the option of checking behind. If the other player bets, you may simply call their wager and end the action.
If you wish to play a larger pot, you may bet or raise while the action is on you. You cannot check while you are out of position and expect your opponent to check and let you see a free card. You also cannot bet and be sure that your opponent will either fold or call you (thus keeping the pot small).
Free cards
When playing drawing hands, there are instances when you would prefer not to pay the cost to progress to the following post-flop street. If an opponent checks to you when you are chasing a draw and checks behind to see the next community card, you have the option to take a "free card" if you have a position over them.
Assume you opted to play suited connectors and have 9♥10♥ on a J♥4♠3♥ flop. Your opponent, who must act first, chooses to check. You may bet; however, you can also check back and get a "free card" to determine whether you can make your flush.
However, if you were the first to act, there is no guarantee that your rival will not bet and force you to pay to stay in the hand if you check.
Summary
Most of your win rate stems from playing in position; mastering this skill will substantially boost your winnings. A solid understanding of position is sometimes more important than our hole cards.
