Pin, Skewer and X-Ray Explained. Three Line Tactics Compared

The pin. What gets exposed

You have already seen what a tiny pin can do to a piece of fabric. On the board, the problem is what gets exposed when something moves. A pinned piece cannot or should not leave the line it is on, because a more valuable piece stands behind it.

An absolute pin forbids exposing your own king. If the knight tried to jump away, the move would be illegal. It does not mean every pinned piece is frozen in every direction. A rook, for example, may still be able to move along the pinning line.

Replace the king behind the knight with a queen. The knight can legally move away, but doing so may lose the queen. That is a relative pin. Sometimes a stronger threat can justify breaking it.

The pin in 35 seconds. Watch on YouTube

The skewer. The king steps away

Now reverse the important relationship. Put the king in front of the rook. We have changed which piece faces the attack first. Time for the barbecue.

The king has to step out of the line, for example to d6, and then the white rook takes the rook that was hiding behind it. The valuable piece in front moves away and the piece behind pays the price. The pinned knight had to stay because its king was behind it. The skewered king has to get out of the way, exposing its rook. The alignment is similar, the consequence is very different.

The skewer in 40 seconds. Watch on YouTube

The x-ray. Influence through a piece

Now for the scanner. X-ray is about influence beyond an intervening piece. It can describe hidden attacking pressure or hidden defensive support. This example shows why a piece that looks undefended may be dangerous to take.

If the black rook takes the bishop, the white rook takes it back. Black has exchanged a rook for a bishop, a tempting capture that comes at a price. This is a lesson in what to look for, not a forced line. Notice that this was neither a knight trapped in front of its king nor a king driven away from its rook. The trick was the defender behind the enemy piece, and we had to see beyond the first obstacle.

No piece jumps through another. The normal movement rules still apply. You may also hear x-ray used more broadly, including for related line tactics, and the labels can overlap.

The x-ray in 45 seconds. Watch on YouTube

A quick test

Here are three positions to recognize. A knight shields its king from a rook. Can it jump aside? No, that would expose its king, so it is an absolute pin. Now the king stands in front of its rook and a rook checks down the file. The king steps away and the rear rook is lost, so it is a skewer. Finally, an enemy rook stands between our rook and our bishop. Taking the bishop lets our rook recapture, so the hidden support changes the value of the exchange, and it is x-ray defense.

• A pin restricts leaving.
• A skewer exposes what is behind.
• An x-ray reveals influence through an obstacle.

So inspect the whole line. For another trick that uses a piece standing in a line, read about the discovered attack.

Watch Pin, Skewer and X-Ray in motion

All three tactics in one animated lesson, with a short video for each tactic in the sections above.

The three and a half minute comparison. All three tactics in one animated lesson. Watch on YouTube

Keep reading after Pin, Skewer and X-Ray

More articles on the same ideas

• Discovered AttackOne piece steps aside and another strikes. Discovered attack, discovered check and double check.
• Four Mating PatternsLadder, smothered, back rank and Arabian mate. Checkmate is not magic, it is geometry.
• The Immortal GameAnderssen gave up a bishop, two rooks and his queen, and still won in 23 moves.

Where this is explained further

• Chess puzzlesSpot pins and skewers on real positions.

Sources for Pin, Skewer and X-Ray

• The positions are simplified teaching positions, each checked with a chess program. The lines shown are examples, not the only legal moves.
• Chess.com, Pin
• Chess.com, Skewer