Kiritsuma, a gable roof, is the generally triangular portion of a wall between the edges of a sloping roof. The shape of the gable and how it is detailed depends on the structural system being used (which is often related to climate and availability of materials) and aesthetic concerns. Thus the type of roof enclosing the volume dictates the shape of the gable.
Yosemune, a hip roof, or hipped roof, is a type of roof where all sides slope downwards to the walls, usually with a fairly gentle slope. Thus it is a house with no gables or other vertical sides to the roof. A square hip roof is shaped like a pyramid. Hip roofs on rectangular houses will have two triangular sides and two trapezoidal ones. A hip roof on a rectangular plan has four faces. They are almost always at the same pitch or slope, which makes them symmetrical about the centerlines. Hip roofs have a consistent level fascia, meaning that a gutter can be fitted all around. Hip roofs often have dormer slanted sides.
Irimoya, a gablet roof (in Britain) or Dutch gable (North America and Australia) is a roof with a small gable at the top of a hip roof. The term Dutch gable is also used to mean a gable with parapets.
A drawback of a hip roof is its reduced available attic space for a given roof pitch. compared to simple gable roofs. In Mediterranean climates with lower snow loads, high roof pitches look out-of-place, making hip roofs impractical. Yet simple gable roofs are also problematic, since there are important advantages to having lower eaves that overhang the perimeter of the house, such as reduced solar gain of the structure during the hot summer months, and a significant rain "shadow" on the perimeter of the house. This rain "shadow" greatly reduces the moisture content of the soil, thus inhibiting both foundation decay, and subterranean termites, which are common in these areas.
These advantages of the gablet roofline offset the additional framing complexity. A gablet roof combines the benefits of both the gable and the hip roof while adding additional architectural interest.