Explanation
The target square is the point where the moving piece arrives. Before the move, the piece occupies its origin square; after an ordinary move, it occupies the target square. The target's coordinates describe the result and help determine whether the piece could reach it.
If an opposing piece occupied the target, that piece is normally removed as part of the capture and the moving piece takes its place. A friendly piece can never occupy the target square; trying to move onto it is illegal.
The capturing piece occupies the target
Initial position
The sequence begins from the standard legal starting position.
En passant is an important visual exception. It is a special capture available immediately after an opposing pawn advances two squares: the capturing pawn finishes on a target square that was empty, while the captured pawn is removed from a different square. In or another promotion, the target is also the promotion square, and the new piece acts there immediately.
The capture ends on an empty square
Before the double advance
The white pawn is on , the black pawn is on , and Black is to move. No en passant right exists yet.
Legality requires more than geometric reach. The route may be blocked, a special condition may be missing, or the move may leave the moving side's king attacked. A king, in particular, cannot use an attacked square as its target because that would cause .
Sources
- 1.Target Square, Chess Programming Wiki
- 2.Article 3: The Moves of the Pieces, FIDE Rules Commission
