[3] Only line pieces (i.e. bishops, rooks, and queens) can skewer; kings, knights, and pawns cannot.
Compared to the pin, a passive action with only an implied threat, the skewer is a direct attack upon the more valuable piece, making it generally a much more powerful and effective tactic.
Black is likely to move the queen, which is more valuable than the rook, but the choice is still available (unlike the king being skewered as above).
In the game Nigel Short–Rafael Vaganian, Barcelona 1989,[4] White sacrifices a bishop to win a queen by a skewer.
For example, if either defending piece leaves the skewer to give check, the other can be rescued on the next move.