Black’s queen is about to take yours for free. Your initial impulse might be to retreat your queen or play QxQ. Maybe one of those moves is right, but don't play either until you have asked whether they can be fit into an offensive plan. White’s most advanced knight is on a dark square; so are Black’s king and one of his rooks, suggesting a fork at f7. Before you do anything you ask whether the needed square is protected, and how many times. Again, twice—by Black's bishop and queen. Unless you can eliminate both defenders of f7, no fork. Each of the defenders is attacked once: the Black bishop by your rook at d1, and the Black queen by your queen. The natural thought is to try QxQ, which you were considering anyway for defensive purposes, and then to notice that Black’s recapture, BxQ, leaves the forking square f7 loose for your knight. Capturing one of the two guardians in the right order thus takes them both out of commission. And it gets better still: once Black's bishop on d5 is out of the way, White's rook on d1 attacks the Black rook on d8. So when White plays the fork, as he now can, he can use his knight to take the d8 rook without fear of recapture by the Black rook on e8.