Pyramid shapes are virtually everywhere; they are prominent in the world of architecture and in works of art. Well-known examples include the Luxor Hotel in Las Vegas, the Great Pyramid of Giza and various graphs used to describe orders of importance.
Pyramids always have a base and three or four triangular sides that meet at a vertex. There are two main types of geometric pyramid shapes, square pyramids and triangular pyramids, or tetrahedrons. A square pyramid consists of four triangular sides and a square base. A tetrahedron consists of four equilateral triangles, and no matter which way it is turned flat, there is one triangle at the base and three sides.
Perhaps the most famous of all pyramid-shaped objects are the ancient Egyptian pyramids on the Gaza plain. Built with millions of stone blocks over a 20-year period around 2560 B.C., they served various functions, most notably as the chambers of the pharaoh Khufu and his family. The main pyramid is the oldest of the Seven Wonders of the Ancient World. The Luxor Hotel in Las Vegas, built in 1993 to house a casino complex, was modeled after the Great Pyramid of Giza.
Pyramid shapes are sometimes used as graphics to demonstrate an order of importance. Generally, items of less importance are placed at or close to the base levels, which build up to the most important item at the top, or the order can be reversed if it makes more sense to the topic. Journalists usually write news in the "inverted pyramid" style, which places the most critical information first, and builds down to less important information.