An angle is a bent metal bar that forms an L-shape, used as a structural element in buildings. It can be made of various materials and is an important tool in construction. Angles provide rigidity and strength to connect different building materials and components. The document discusses various tools used in construction, metalworking and welding such as allen wrenches, chisels, drills, grinders, levels, and wrenches. Many of these tools are used to shape, cut, grind or join metal materials and components for buildings, bridges or other structures.