The Skewer
A skewer is the pin's mirror image. A valuable piece (often the king) is attacked along a line; when it moves out of the way, the piece behind it is captured.
After Rh8+, the king on b8 must step aside and the rook captures the queen on a8 — a classic skewer.
How it works
Skewers work along ranks, files and diagonals using the long-range pieces — rook, bishop and queen. Check the more valuable piece (or the king); when it moves, take what was hiding behind it.
Pin vs. skewer
In a pin the less valuable piece is in front; in a skewer the more valuable piece is in front. Both exploit pieces lined up on the same line.
Practice this pattern
Real positions where a the skewer wins — tap a puzzle to solve it, or train the theme endlessly.