Tactics & checkmates
Skewer
A skewer is a line attack with the more valuable or urgently threatened target in front. When it moves, the piece behind becomes exposed. Bishops, rooks and queens can skewer along diagonals, ranks and files.
A practical example
A white rook on a1 checks the black king on a5, with a black rook behind it on a8. If the king must leave the a-file and Black has no better defence, Rxa8 follows.
A common mistake
Assuming the rear piece is automatically lost. The defender might capture the attacker, interpose a piece or keep the rear piece protected with the king. The actual position matters.
Try this in your next review
Look for kings and valuable pieces on the same line. Calculate every legal response to the check before deciding whether the second piece can be won.
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