This document discusses compression members and buckling behavior. It explains that columns and struts can be categorized as either short or long, with short columns experiencing compressive strain under loading and long columns becoming unstable and buckling under a normal deformation. Buckling resistance is highest for members that are short and stiff with high bending resistance, and lowest for members that are long and slender. The document focuses on buckling behavior of steel structural members, which tend to be more slender than concrete members, and notes that both global and local buckling are instability phenomena that should be avoided through adequate safety margins.