Examples

White can weave a mating net with Bh6.
Black has no defence against Qxg7#.

Black's king is in big trouble as it is surrounded by enemy pieces.
Rf7+ looks strong, but allows the king to escape via e4.
However, White can guard the escape square first, and win with the quiet move f3, after which Black has no defence against Rf7#.

White can weave a mating net with Bh6, threatening Qxg7# and also Bxg7#.
Black's defence is insufficient.
Rxe7 protects against Qxg7#, but not against Bxg7#.
Rg8 allows Qxg8#.
And gxh6 opens the diagonal, and allows Qxf6#.