Joseki of the week 1

This is the second in the series of joseki that may be posted occasionally weekly.

The diagram shows a 4-3 pincer joseki. Here black plays at 5 instead of the more common a or b.

White would like to connect 2 and 4 from the above diagram, but can’t immediately succeed.

The correct move is for white to play D18 first.
Now if black saves C15, white can trade and capture D16-17,
which is usually a happy result for white.