A very common roof type the hip roof (or hipped roof) does not have flat sides like the gable roof instead all sides of the roof slope down to meet the walls of the house. Building a hip roof is more involved than a gable roof but building the walls for such a house is actually easier as they are all the same height.
Hip roofs are very good for homes in high wind or hurricane areas as they offer better internal bracing and are less likely to be peeled from the house as a gable end. Given the roof is at a uniform height gutters can be easily attached around the entire house. Also, the roof protects more of the house from elements such as sun, wind and rain which over time can require increased maintenance for the structure.
Hip roofs offer less internal roof space making access for maintenance more difficult and offering less potential storage space. Cross hipped (and more complex hip roofs) need to have their valleys kept free from debris so that moisture and dirt don't cause a failure of the valley flashing.
Common variations of hip roofs:
Simple hip roof The most common hip roof has a ridge over a portion the roof creating two polygon sides and two triangle sides of the roof.
Pyramid hip roof Four equal triangular sides meet at a single point at the top of the roof.
Cross hipped roof Similar to putting two hipped roof buildings together. Where the two roof sections meet forms a seam called a valley.
Half hipped roof A standard hip roof that has had two sides shortened to create eaves.
Dutch gable A hybrid type of gable and hip roof where a full or partial gable is located at the end of a ridge offering more internal roof space and/or increased aesthetic appeal.