A brick is a block or a single unit of a kneaded clay-bearing soil, sand and lime, or concrete material, fire hardened or air dried, used in masonry construction. Lightweight bricks (also called lightweight blocks) are made from expanded clay aggregate. Fired brick are the most numerous type and are laid in courses and numerous patterns known as bonds, collectively known asbrickwork, and may be laid in various kinds of mortar to hold the bricks together to make a durable structure. Brick are produced in numerous types, materials, and sizes which vary with region and time period, and are produced in bulk quantities. Two most basic categories of brick are fired and non-fired brick. Fired brick are one of the longest lasting and strongestbuilding materials sometimes referred to as artificial stone and have been used since circa 5000 BC. Air dried bricks have a history older than fired bricks, are known by the synonyms mud brick and adobe, and have an additional ingredient of a mechanical binder such as straw.