In this reading Ching talks about the different kinds of structures and their functions . He explains that a structural force is any influence that produces a change in the shape or movement of a body. It is considered to be a vector quantity possessing both magnitude and direction. There are also different types of forces like collinear forces which occur along a straight line, and a concurrent force which have lines of action intersecting at a common point. He also speaks about structural equilibrium which in both structural design and analysis, we are concerned first with the magnitude, direction, and pain of application of forces, and their resolution to produce a state of equilibrium. Columns are also introduced in this section and they are rigid, relatively slender structural members designed primarily to support axial compressive loads applied to the ends of the members. There are also different types of beams with different purposes as well.