Pediments are a form of gable in classical architecture, usually of a triangular shape. Pediments are placed above the horizontal structure of the cornice, or entablature if supported by columns. In ancient architecture, a wide and low triangular pediment typically formed the top element of the portico of a Greek temple, a style continued in Roman temples. But large pediments were rare on other types of building before Renaissance architecture. For symmetric designs, it provides a center point and is often used to add grandness to entrances.

A gable is the generally triangular portion of a wall between the edges of intersecting roof pitches. The shape of the gable and how it is detailed depends on the structural system used, which reflects climate, material availability, and aesthetic concerns. The term gable wall or gable end more commonly refers to the entire wall, including the gable and the wall below it. Some types of roof do not have a gable. One common type of roof with gables, the 'gable roof', is named after its prominent gables.