Poker beginners might find the subject of poker betting to be a complex one, but with some study and game practice the betting actions will become much easier to follow. The first area of Texas Holdem poker betting is covered in the game rules - and involves understanding betting rounds, how each round progresses, how to place bets and when, and how the blinds operate. All of these are covered in the poker rules section of this site.
Here I'd like to focus on the second area of poker betting, which covers the betting limits of different types of games - known as no limit and limit betting - which determine the amount you are able to bet at any point in the game.
Generally you'll find that low limit games involve risk of smaller, more controllable cash amounts. Limit games (and especially those with a high limit) are the opposite, presenting greater risks to your bankroll but of course with greater potential winnings. There are less popular betting structures known as pot limit, half-pot limit, and spread limit games.
No Limit Poker Betting
No limit betting refers to games where the size of the bet (in any of the individual betting rounds) is allowed to be any amount between the value of the big blind and the cash available in your stack. When you see two cash amounts used in reference to any no limit poker game (for example "$2/$4 no limit), these two amounts determine the cost of the small and big blinds respectively. Hence the minimum bet will always be the larger of the two amounts, and bets can go up to any amount placed by any player.
Fixed Limit or Structured Limit
Fixed limit poker betting means that the amount that can be bet is a set amount in each betting round of the game. You'll see these fixed limit games denoted by $1/$2 or $4/$6 as examples, with the first number setting the bet size pre-flop, and the second number stating the upper limit of any bets allowed.
As an example, in a $1/$2 hame you'll be betting $1 each time you want to see the flop, but you'll need to place $2 bets for each subsequent round. With a limit of four bets for each player in each betting round (you can bet, face a re-raise, re-raise your opponents, and be re-raised again).
In a Pot limit game, you are allowed to bet any amount between the value of the big blind and the size of the pot at that time on any betting round. When two cash amounts are used in reference to a pot limit game (like "$1/$2 pot limit"), the amounts stated are the costs of the blinds and have no impact on the amount you can bet, except that the minimum bet will be the larger of those two numbers. Often in pot limit poker games, the first person to bet will be allowed to bet 3 or 4 times the size or the pot, although this is sometimes only allowed pre-flop.
Similar to pot limit except a player can bet amounts between the cost of the big blind and up to half of the size of the pot.
Spread limit poker betting is where players can place any bet within a certain range. For example, in a $1-$5 game, a player can bet between $1 and $5 during any betting round. If there are four amounts, like $1-$5-$10-$10, that means you can bet between $1 and $5 pre-flop and on the flop. On the turn it goes up to the 3rd number (between $1 and $10), and on the river it goes up to the last number (between $1 and $10).
If there are three amounts, like $1-$5-$10, that means that you can bet from $1 to $5 during any betting round, but on the river you can bet between $1 and $10. This would be the same as a $1-$5-$5-$10 game.
''....basic introduction to poker betting stuctures. How to understand the types of bets and betting patterns in poker games....."
Additional Links - Poker Betting
Wikipedia covers all areas with an excellent, easy to follow article on poker betting. As always, visual instruction will help so here's a good video guide to the betting types you'll come across in any poker games you play.