Where you sit decides how you play. Here's the 6-max and 9-max table map, and how to play every seat from the button to the blinds.
acts last on every street · opens ~39%
The best seat in poker. You act last on every street after the flop, so you decide with more information than anyone. Open the widest range from here and attack the blinds relentlessly — position alone wins pots.
acts first postflop · worst seat
You post half a big blind, then act first on every postflop street — the worst spot after the flop. Come in tight, and prefer raising to just calling: you never want to play a big pot out of position with a weak hand.
already in · widest defend
You post a full big blind, so you already have money in and get a price to defend. Call wider here than anywhere else preflop, but don't overplay weak holdings after the flop when you're out of position against the raiser.
first to act · opens ~9%
First to act before the flop, with the entire table still to come. Open only your strongest hands — every player behind you can wake up with a monster, and you'll be out of position on all of them.
still early · opens ~14%
A step better than under the gun, but still early. Widen your opening range a little, while respecting that the cutoff, button and blinds still get to act behind you. In 9-max this is where UTG+1 and the lojack sit too.
second-best seat · opens ~23%
One seat before the button, the second-best position at the table. Open a wide range and go after the blinds, especially when the button looks likely to fold. In 9-max the hijack sits just to your right.
UTG is 'under the gun', the seat directly left of the big blind and the first to act before the flop. With the whole table still to come, it calls for the tightest opening range.
The button marks the dealer seat and acts last on every postflop street. That last-to-act edge makes it the most profitable position, so you play the widest range from there.
Clockwise from the dealer: button (BTN), small blind (SB), big blind (BB), then under the gun (UTG), middle position (MP) and the cutoff (CO) in 6-max. Nine-handed adds UTG+1, the lojack and the hijack.
Acting later means more information when you decide. That single edge lets you bluff more, value bet thinner and control the size of the pot, which is why later positions win more money.