Poisoned Play

Here is a game from the 2008 Corus Group C event, GM Negi - GM Grivas with full annotations and commentary:

This is a good example of the dangers of taking a "poisoned" pawn or piece. In this game black decided to play ambitiously with Qd5 and then Qxg2 which lead to the queen being misplaced and open lines for white to attack and exploit the position of the black queen. Before you take a free pawn like this you must always take a good look to see and understand the compensation for the side which is sacrificing the material.