Preflop fundamentals

Six seats. Under the gun acts first before the flop and stays near the front on every street after it. The button acts last after the flop, every street, without exception. That one fact is why the same two cards can be a clear raise on the button and a clear fold under the gun.

Acting last means everybody else has already committed before you decide. You know who checked, who bet, and how much, and you choose the size of the pot holding more information than anyone else in the hand. Acting first means guessing, and then paying for the guess.

The blinds look like an exception and are not. They act last before the flop because their money is already in, and then act first for the rest of the hand. That is the worse half of the trade, and it is why the blinds are the two seats that lose money over a lifetime.

Under the gun, five players are left to act. On the button, two, and both of them are in the blinds and will be out of position for the rest of the hand. So the button opens around three times as many hands as under the gun. This is not a matter of style or table image. It is the arithmetic of how many chances there are for somebody behind you to have something.

You do not have to memorise the charts as pictures. Learn the shape and the charts stop being a list: pairs and big aces open from anywhere, suited broadways come in next, and weak aces, suited connectors and the junk that plays well multiway only open once most of the table is already behind you.

The small blind posts half a big blind and the big blind posts one, before anybody has seen a card. That money belongs to the pot now. A hand you would never have played for a raise does not become playable because some of the raise is already yours.

The small blind is the hardest seat at the table to open from, which surprises people, because it acts second to last before the flop. The reason is what happens next: the big blind is directly behind, will call more often than anyone else because of the price, and will have position on you for every remaining street. So the small blind opens tighter than the button despite acting later.