Depending on the poker game you’re playing, you’ll usually find yourself playing with one of three types of betting structures; Limit, Pot Limit or No Limit.
In Limit, there is a pre-determined betting limit applied in each game and in each round of betting. Let’s take for example a $2/$4 Limit Holdem cash game:
The small blind will be $1 and the big blind $2.
If you raise preflop, you’ll have to raise by $2 at a time, and there will usually be a cap on the number of reraises (usually 1 bet plus 3 raises) that can be done.
On the flop, the initial bet allowed will again have to be $2 with possible raises of $2 at a time for a maximum of 3 raises/reraises.
On the turn and river, the initial bet allowed will now have to be $4 with possible raises of $4 at a time with a cap once again.
In Pot Limit, the maximum bet a player can bet is what is in the pot. So for example, if there’s $30 in the pot at the beginning of the round, player A can bet $30; player B, who acts after him, would be allowed to then raise $120 (after the bet by A, the pot was $60 with $30 to call by B, so a $90 pot, hence $30 for the call and a $90 maximum raise).
Now, depending on where you play there might by some differences as to how the small blind is interpreted for the pot preflop. Some places consider that the small blind is only half of what is (virtually) in the pot: so let’s say the small blind is $10 and the big blind is $20, the pot would be considered to be $40 and not just $30, so the first player to act could raise $80 (pot is $40 with $20 to call, so a $60 pot, hence $20 for the call and a $60 maximum raise).
Finally, in No Limit, it’s short and sweet. A player can bet all of his/her chips at any time.