A pin the other way round: the valuable piece is in front, and when it moves, the one behind falls.
Check, then take
A skewer: check the king along a line, and when it steps aside, take the piece behind it.
A skewer is a pin turned round. In a pin the lesser piece is in front and dare not move; in a skewer the more valuable piece is in front and must move, leaving the one behind.
The queen can be skewered too: attack her with a defended rook or bishop, with a rook behind her on the line. If she takes, she is taken back; if she moves, the rook falls.
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