Check
Check means the king is attacked. The side to move must get out of check. There are three ways: move the king, capture the checking piece, or block the line.
A knight check cannot be blocked, because a knight jumps. You must move the king or capture the knight.
You may not move the king onto an attacked square, and you may not move a pinned piece if that leaves the king in check.
Double check, where two pieces give check at once, cannot be blocked and cannot be answered by a single capture unless that capture takes a piece with the king. The king has to move.
On the board
8
7
6
5
4
3
2
a1
b
c
d
e
f
g
h
White is in check from the queen on h4. Move the king, block the diagonal, or take the queen. Any legal move answers the check.
Common mistakes
- Ignoring a check to take a piece. The king must be made safe first.
- Blocking a knight check. A block does not stop a knight.
- Castling out of check.