Figure 5.1.1.4[Black to move]

You want to be thinking all the time about any enemy pieces you can capture and what guards them. Here Black would like to play KxR, but the rook is guarded by a pawn. But he can take out the pawn with Rxf5; once White recaptures (RxR+) the White rook on g6 is left loose, so Black takes it with his king. He nets a pawn and takes control of the rest of the game.

We have seen that pieces tend to be especially vulnerable when they are guarded by other pieces rather than by pawns. But as this position shows, even an enemy piece protected by a pawn may present an opportunity to make gains.