This document discusses different types of lintels and arches used in building construction. It defines a lintel as a horizontal beam over an opening that carries the weight above it. Lintels are classified by material - timber, stone, brick, steel, and reinforced concrete. Stone lintels are most common and can span up to 2 meters. Reinforced concrete lintels have replaced other types due to strength, fire resistance, and ease of construction. Arches are curved structures that support weight above an opening. Key terms related to arches include intrados, extrados, voussoirs, crown, spandril, abutment, and pier.