Examples

Black can sacrifice the queen with Qxh3+!
Recapturing lures the king to h3, where it can be attacked with the discovered check f4+.
The pawn attacks the queen on e3, and also discovers a check by the bishop on e6.
Black regains the queen, and has won a knight.

The decoy can also be on the piece attacked directly, as in the following example:

Bobby Fischer was 14 years old, and on his way to his first US championship, when he won this game with the queen sacrifice Qxc1!
If Black recaptures with Qxc1+, the Queen is lured to c1, where it can be attacked with the discovered counter-check Rf1+.
After Black deals with the check, White can capture the queen, and has won a rook.
In the game Black continued with Qh4 instead of recapturing, but was a rook down and soon resigned.

Related combinations

It is also possible to decoy a piece to a square where it can be attacked in a subsequent tactic other than a discovered check. And you can decoy the king into checkmate.