Fork
A fork or double attack creates two threats at the same time, so the opponent cannot answer both.
What to look for
Look for checks or attacks that hit the king, queen, rook, loose pieces, or mate threats at once.
Recognize the mechanism
Compare candidate moves by the number of concrete threats they create. After finding two targets, calculate the strongest reply: the opponent may save one target with check, capture the forking piece, or create a stronger threat.
Common practical mistake
Two attacked pieces do not guarantee a gain. A fork must survive the opponent’s forcing reply; target value alone is not a substitute for calculation.
Training goal
Train your eye to find moves with two purposes.