Check
Check is a chess term. When someone's King is attacked, as in he could be captured in the next move, that King is in check.[1]
When your King is in check, you must get him back out of check with your next move. Either you can capture the checking piece, or your King can flee to a flight square, or you can interpose another piece.
If you can't do any of these things, if there's no way to avoid your King staying in check, then that's checkmate, and you've lost the game.
Naturally, you're not allowed to voluntarily place your own King in check.
References
- Chess: Theory and Practice Howard Staunton, 1876, pp. 48—49
Chess terms: Attacking | Broad centre | Capturing | Check | Hanging | Interposing | Line piece | Material | Open file | Piece | Reply
