And now a last related idea. We have seen that a first principle of tactical play is the importance of inspecting checks you can give and your opponent's responses. A second and related principle is the importance of experimenting with any mating threats you can create—most typically by directing a second piece at a square next to the enemy king that you already attack once. Here is a simple example. White’s queen hovers near the Black king. The situation is tense because White’s knight is pinned, but White does have one obvious offensive possibility: h5-h6, where his pawn then is positioned to provide cover for Qg7# next move (it follows the formula: the pawn adds an attack against a square already attacked once by White's queen). Black can’t allow this. And since he is unable to move his king, he has no choice but to take out the pawn with Nxh6. White asks what would then be possible. Returning to first principles, he looks for any checks he would be able to give and any forks he might inflict in the process. This leads to Qf6+, winning the loose knight.
Soon we will look more closely at uses of mating threats to create queen forks, but the basic principle is clear enough: a mate threat that doesn't at all work to create mate may work wonderfully in other ways—viz., to create a loose piece. In this case the point of the mate threat created with h5-h6 had nothing to do with actually achieving mate. The point was to force Black to rearrange his pieces in a way that would lead to new tactical shots. Try thinking about mate threats in this way: as a means to an end other than mate.