Pediments are gables, usually of a triangular shape. Pediments are placed above the horizontal structure of the lintel, or entablature, if supported by columns. Pediments can contain an overdoor and are usually topped by hood moulds. A pediment is sometimes the top element of a portico. For symmetric designs, it provides a center point and is often used to add grandness to entrances.

The tympanum, the triangular area within the pediment, is often decorated with a pedimental sculpture which may be freestanding or a relief sculpture. The tympanum may hold an inscription, or in modern times, a clock face.

Pediments are found in ancient Greek architecture as early as 600 BC (e.g. the archaic Temple of Artemis). Variations of the pediment occur in later architectural styles such as Classical, Neoclassical and Baroque. Gable roofs were common in ancient Greek temples with a low pitch (angle of 12.5° to 16°).