This document discusses different types of structures. It defines structures as elements that exist together to form something that is man-made or natural. It then describes five main types of structures: truss structures, cable structures, arch structures, framed structures, and surface structures. For each type, it provides a definition and examples of how it is used in engineering. It explains that trusses are lightweight and sturdy systems used for rooftops. Cables only support tension and are used in suspension bridges. Arches distribute force into compression and eliminate tension. Framed structures form a skeleton of beams and columns. Surface structures use membranes like tents to distribute force through tension.