X-Ray Attack, Definition 1, Attacking X-Ray (Skewer):
Part of the Chess Tactics Guide

Chess Tactics Guide
X-Ray Attack
[Definition 1: Attacking X-Ray (Skewer)]

Definition 1: It's another term for Skewer Attack, when you directly attack one of your opponent's important pieces, which happens to be in front of a relatively minor, but still influential Piece, and you force the piece at the front to step aside, in order to capture the piece behind.

In this example, White's Be4, supported by Qe1, performs the attacking
X-Ray through Black's
King, with sights firmly
set on Black's Qa8.

Move 1, White's Bishop slides onto c2, attacking Black's Queen, at a4; Black's Queen evades the threat and counters with one of her own, on a5, placing White's King in "Check" (+).

But, on closer inspection, Black's Queen is performing an X-Ray Attack (Definition 1), on White's King and Queen. The X-Ray/Skewer Attack is forcing the more-important piece - White's King - to move and expose the rearward piece - White's Queen - to potential capture.

For this example, Black's Queen doesn't capture White's Queen but, rather unwitting, puts herself into jeopardy, for the sake of a second
X-Ray/Skewer example ...

Move 2, White's King steps out of Check, down onto d1; Black's Queen - her female senses maybe distracted by an imaginary shoe shop - strides up to a8.

Note: This position has Black's King infront of his Queen ... See that, with both White's Bishop and Queen able to work on the White diagonals, conditions are right for a Skewer Attack ...

Sort of like the one coming up ...

Move 3, White's Bishop speeds up to e4, putting Black's King in "Check" (+) and creating an X-Ray Attack, with Black's Queen the victim ...

Black's King has no option and steps out of the way, to d6 and exposes his Queen to her fate.

Move 4, White's Bishop captures (x) Black's Queen, on a8, to complete this 2nd Definition example.

And that completes this example of an X-Ray Attack (Definition 1).

Moving On: X-Ray Attack, Definition 2 (Page 3).