We have seen that if you pin the enemy queen to its king, the queen always will, in principle, be able to take the piece that pins it. The reason, of course, is that the only pieces capable of imposing a pin are your bishop, rook, and queen, and the enemy queen can move in the same way as any of them. This generally means that any piece that pins the queen requires protection. (There are exceptions to this statement that we will consider later, but it holds as a general rule.) We already have seen the point a few times, so here we need spend only a few examples on techniques for bringing the needed protection into existence.
This first position is an easy illustration of the goal. White sees Black’s king and queen on the same rank. The way is clear for him to impose a pin with Ra8. But before pinning the queen, a piece needs protection—something to prevent Black from playing QxR. He has it in his bishop. Thus Ra8 safely pins and wins the queen for a rook.