We have examined how to make the pinned piece a suitable target and how to get your pinning piece onto the square it needs. But every example of both issues has started with the observation that an enemy piece is aligned with its king. Our next task is to learn how to create that alignment when it doesn’t already exist. The principal tools we will use here are checks that push the king into a line with one of its fellow pieces, or that require an enemy piece to jump into line with its king to protect it. Or sometimes a capture may require a king to recapture and cause it to walk into a pin.
The core idea is illustrated to the left. White has no pins or other tactical openings at hand. He might follow the standard practice of examining the consequences of any checks he can inflict. There are two: Rxg7 and Ra8. The first of those loses the rook to KxR, but Ra8 is more interesting. Black has just one safe reply: Kf7. White sees that this brings Black’s king onto the same file as his bishop—and immediately causes the bishop to be pinned, since White already has a rook on the f-file. Black’s reply to the check thus makes his bishop a sitting duck, so the question for White is how to attack it. Pawns are best for the purpose wherever they're available; here White plays e4-e5 and uses the pawn to take the bishop a move later.
Now try to start not by looking for checks but by just seeing the visual pattern: the White rook aimed not just at the Black bishop but through it. . . and almost at the Black king, which is one file away. If only the Black king were on f8, just behind the bishop—so you look for a check that nudges the king that way.
When you see an idea like this, it's a good habit to think about the move order and ask what happens if you fiddle with it. Here the thought might be to start with e4-e5. Then if Black plays Bxe5, White has Ra8 and mates. Or does he? You have to be mindful of all of Black’s resources. He has a rook on b3, and so can reply to White’s Ra8 with Rb8—where the Black rook would take protection from the bishop then on e5. So it’s better to start with the check, create the pin, and then go after the bishop; but it's important to see both variations, because the second one almost is better.