Texas Hold'em has exploded in popularity in the last few years following the win of amateur player who made millions in the world series of poker. Texas Hold'em has been around for a long time but only got recognition now for the great game that it is. Just search poker on Google and you will find all sorts of websites offering poker strategy, videos, software, hand trackers, statistic trackers, etc.
Texas Hold'em requires skill, and the best players are always the ones who do no depend on luck and play with odds in their favor. In short run however a donkey (slang term for a bad poker player) can beat the shark (the professional player), due to the luck factor. You must understand that in the short-run there is luck involved, but it will eventually even out after thousands of hands. This is where the Theory of Poker comes into play. The professional players know that losing is part of the game and you are bound to have at least one losing session in your poker career.
Poker is based on a lot of theory and math. First thing to consider when playing poker is whether you have enough money to play with. Sure you might have $20 and take that to a 10c/20c table, but what if you get a bad beat? You must follow proper bankroll management. A general rule is that you must have 20 buy-ins for a cash table. For example, you need $400 to play 10c/20c. The theory behind this is that when you sit on a table, in the short run your opponent might get lucky and take your whole stack. If you only have one buy-in, then you can lose all that money in one unlucky hand and then never be able to play again.
The bankroll management theory states that a poker player more money than a single buy-in to play to the best of his ability. Poker money must be set aside only for poker and not for personal use. This way you can climb up limits and start playing higher stakes. If you lose, you can easily drop down a stake and still have enough money to come back. Bankroll Management must be followed at all times, because it is one of the most fundamental theories, without which you are bound to go broke.
Then comes the pot odds theory. Pot odds refer to the money in the pot and the strength of your hand. This way you can make a mathematically correct decision and make money in the long run. For example, imagine you are button on a $1/$2 game, and you are holding 78s. Everyone calls and according to the pot odds, you can profitably call as well. Why? Because everyone behind you just called making the pot a total of $15, plus the big blind and small blind. You are only risking $2 to win $15. If you happen to hit a straight, flush or even better a straight flush, then you can easily win a huge pot.
The theory behind the pot odds is that in the long run if math odds are in your favor, then you will win. For example if you play in a situation where you are 70% favorite every time, then 70% of the times you will come home as a winner and make money in the long run. Now of course the opponents will win 30% of the times, but you will win more. You will lose sometimes but over a huge sample of hands, your winning percentage should be closer to 70%. If you have the correct pot odds, then you must make the call even if you think that you are behind in the hand. Pot odds are very essential in order for you to become a successful poker player. Many books and calculators are available that can provide you in-depth pot odds for every decision.
There are also lots of theories behind tournament such as stealing blinds, playing premium hands under the gun, stealing from the button, re-stealing from an original blind stealer, defending blinds, etc.
The theory behind stealing blinds is that in a tournament the blind levels do not stay at the same level. The constantly go higher and stealing blinds can get you a lot of chips late in the tournament. Also during the late stages you will find conservative players who will fold every hand to get more money. These players are not playing for the first place, but for some extra money. As a professional player you must make stealing blinds an essential move in tournaments. This way you can safely add to your chip stack and take advantage of players.
Stealing blinds from the button is the most effective. If everyone behind you folds and the blinds are really high, then you only have to face small blind and big blind in order to steal their blinds and also you have position after the flop in case you miss the flop completely.
Defending blinds is a controversial theory which states that you should defend your blinds more often in the late stages, because other players will be trying to steal your blinds. If you call their raises, you are constantly putting pressure on them. But what if they are not stealing and actually have a good hand? This is why blinds should only be defended against small raises or if you are an expert poker player who knows what he is doing.
These are some of the basic theories of poker for cash games and tournaments. Poker requires tremendous amount of skill. For a beginner it may seem hard to understand the skill factor, and that is why they lose their money because they are gambling not playing poker. You should always look for poker strategy articles, videos, and books which will improve you significantly. Remember that poker school is a school that no one graduates from!