We have looked at cases where you pin pieces in order to take what they are supposed to protect. But the power of pins against pawns for the same purpose mustn’t be overlooked, either. Pawns serve critical defensive purposes; they make ideal guards for pieces. If you can pin a pawn you thus may be able to leave an enemy piece exposed to capture.
To the left is a simple example. Black scans the lines out from White’s king and finds a pin of the g2 pawn already in place. The automatic question is what the pawn appears to protect—what pieces, what squares—and how you might take advantage of its paralysis. Here the g2 pawn protects the knight on h3—or rather it's supposed to protect the knight, but can't. Black takes it with QxN.