Shear Force Diagram is a graphical representation of shear force (V) along the length of a beam subjected to external loads. It is an analytical tool used in structural design to determine member type, size, and material. There are two methods for constructing SFDs - basic and integration. The basic method involves determining support reactions, sectioning the beam, drawing free body diagrams, and calculating shear and moment as a function of position along the beam. SFDs can be used to find maximum shear values, bending moment diagrams, and deflection of beams under different loading conditions such as concentrated, uniform, and variable loads as demonstrated in the examples.