Pin or discovered attack

A useful x-ray is one line: a rook, bishop, or queen through exactly one piece, onto a target that is undefended or more valuable. This habit names that line.

It is a pin when the piece in the middle is the same color as the target. It is a discovered attack when the piece in the middle is the same color as the attacker.

Why you should notice it

The same picture is two different ideas. A pin says the middle piece cannot step aside without exposing what stands behind it. A discovered attack says the middle piece is yours, and moving it uncovers the line.

When to check it

During threat assessment, look at their useful x-ray and ask which of the two it is. While finding the best move, do the same for your own line. You are naming the pattern, not hunting a combination.

Why players miss it during games

Both patterns share the arrow and the piece in the middle, so they get lumped together as "some x-ray". The color of that middle piece is the whole distinction, and it is easy to skip once the line is already obvious.

How WayChess trains it

The useful x-ray is already drawn, with a yellow ring on the piece in the middle. You choose Pin or Discovered attack. The same check is trained on your line and on the opponent's line.

Related checks

Build it on useful x-ray. Pin asks you to find every such pin yourself. Pinned defender is a different check: a piece whose protector is pinned. Walking into a discovered attack asks whether this move lands a piece on a discovered-attack line.

See all habits.