Double Check
A double check attacks the king with two pieces at once. Because answering only one check is not enough, the king must move.
What to look for
Look for discovered checks where the moving piece also gives check. Blocks and captures often do not work against double check.
Recognize the mechanism
Verify two checking attacks in the final position. The usual mechanism moves one piece with check while uncovering another check. Calculate the king’s destination next, because resolving just one attacking line is insufficient.
Common practical mistake
Do not stop calculating at the double-check symbol. The king may still have a safe escape; forcing does not automatically mean mating.
Training goal
Recognize one of the most forcing attacking patterns in chess.