What Do TAG and LAG Mean?
In poker, TAG means "tight aggressive". LAG means "loose aggressive". These are two common styles of play which can describe many of the professional poker players you've seen on television. The term "tight" describes a player who only (or mostly) plays premium hands in which they hold good to excellent cards. The term "loose" describes a player who plays a good number of speculative hands. In Texas hold'em, aggression indicates a player doesn't call very often, but instead raises the pot in order to put pressure on his or her opponent.
Advantages of Tight Aggressive Play
It's sometimes hard for beginning gamblers to visualize this, but a player can be both tight and aggressive. This means the player doesn't play that many hands, but when they do, they bet and raise with aggression. The other players at a table come to realize a tight player, who might play only 15% of the hands or so. Once this player's tightness is noticed, good players tend to get out of their way when they start to bet into the pot. Gamblers naturally have to assume they're going to have the nuts if they're playing, or at least the tight player thinks they have the nuts. In this way, aggressive betting reinforces the tendency of the other gamblers to assume a strong hand, since the other players naturally assume this person wouldn't be involved unless they thought they were going to win the hand. When a player is tight and aggressive, people (with any sense) respect their strong plays. Of course, this makes their bluffs all-the-more difficult to call, because they probably have a strong hand.
Advantages of Loose Aggressive Play
When you play a lot of hands, bluffing is not always as effective. Once the other players at the table realize you're a loose player, they are likely to assume you're bluffing at every turn. In this case, the aggression you show might be a temptation to call, though the size of the bet might scare them off. Unpredictability is the strength of your game. If you have a reputation for cold-bloodedness or even borderline craziness, players never know what you might do. If they consider bluffing you, they know you might come over the top with a bigger re-raise. Or you might play a bad hand just to see if that's what you're doing. The loose, aggressive player is going to have wild swings of fortune. Sometimes, they'll seem brilliant. Sometimes, they'll seem like a fool. If done right, a loose/aggressive poker player can drive their opponents to distraction, making them go on tilt. This also happens to be the favorite style of bad players who've watched to much tv poker, which gives this style of play a bad name.
Is TAG or LAG Better?
When done right, either style can win. Aggression is an important factor (and a weapon) in poker. It's been said that, if you don't have a hand strong enough to raise, you probably shouldn't call with that hand, either. That's especially true after the flop, when you only have 2 chances to improve the hand, instead of 5. Plenty of examples of successful tight/aggressive and loose/aggressive professional poker players exist. It's really not a matter of which is best, but which is better for your personality. In either case, a Texas hold'em player need to understand the fundamentals of the game and be able to calculate pot odds. Many of the loose aggressive players on television are more calculating than you think, while many of the tight aggressive players bluff more than one would think, too.
Low Limit Aggression
A few observations need to be made. Bluffing at the low limit tables must be done with caution. Since the stakes are lower, you might not be able to scare people away from the pot as quickly. Also, low stakes Texas hold'em is going to have its share of newbies, fish, and other types of bad players. In many cases, they don't know enough to be frightened by a bluff.
Also, when you're just learning the game, it's probably better to try mastering the tight/aggressive style first. I'm not saying this is the better way to become a professional Texas hold'em player, but it's a sounder way to stay afloat while you gain experience and move toward mastery. If you're just taken up poker and you decide to mimic Gus Hansen's style, because you think it looks cool on television, you're probably going to botch the hands a lot more than you succeed. Get thousands of hands under your belt before you start to develop an outrageous style.