The skewerThe pin backwards: the dear piece is in front, is forced to move, and leaves behind what stood behind it.

A skewer is a pin back to front. In a pin the cheap piece is in front and cannot move. In a skewer the DEAR piece is in front — and it is forced to move, exposing what was behind. Look at the marks: the black king on e4 and the black queen on e8 are on the same file. If a check comes down that file, the king has to get out of the way.

Give check along the e-file.

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