The area moment of inertia (also called the second moment of area) defines the resistance of a cross-section to bending, due to the shape of the cross-section. It is a key parameter for the analysis of beams and columns. In this video I take a detailed look at the area moment of inertia, how's it calculated, and how it's used. I also cover key related topics, including the polar moment of inertia, the parallel axis theorem and Mohr's circle for moments of inertia.