Special moves
Castling
The king-and-rook move that hides the king and activates a rook.
What is the castling?
Castling is the one move where two pieces move at once: the king steps two squares toward a rook, and the rook hops to the king's other side. It is the fastest way to tuck the king into safety and bring a rook toward the centre.
Why the castling matters
Tactically it cuts both ways. Failing to castle leaves the king in the centre, where most opening disasters happen — and castling itself can be a tactic, whether castling out of a pin or castling to land a rook on an open file with a sudden threat.
How to use it to win
As a rule, castle early and ask questions later — a king in the centre is a target. But always check the in-between: is there a check or capture that exploits the king's trip, or does castling come with gain of tempo?
Try an example puzzle
A real castling puzzle from the app. White to move — find the idea, then reveal the line.
4 
a b 
e h 1 Show solution
1. O-O#
Drill the castling on thousands of real puzzles, matched to your rating.