Roof Hips are generally used on the roofs of houses which have four sloping sides. This is opposed to the traditional roof which has two sloping sides and two vertical sides.
The Roof Hips fit onto the joining top surfaces which meet at an angle. They are generally found more on bungalows, but also seen across many traditional and older style buildings.
There are various styles, including Bonnet Tiles, Valley Tiles, and Hip Tiles