The term LAG in poker stands for “loose-aggressive,” which describes a particular style of play and can also describe a certain player and their general tendencies at the table.
The LAG style of play is characterized by seeing a lot of flops and battling for pots with bets and raises. When done correctly, this particular style can be very tricky to play against, as it constantly puts you in tough spots.
A LAG player is someone who adheres to this style, and these types of players are good for the game because they tend to create a lot of action. While a good LAG can be tricky to play against, a bad LAG who plays like a maniac will donate a lot of money over the long term.