Mohr's circle is a graphical representation of the transformation equations for plane stress. It allows visualization of normal and shear stresses on inclined planes at a point in a stressed body. Using Mohr's circle, one can calculate principal stresses, maximum shear stresses, and stresses on inclined planes. The procedure involves plotting the initial stress state as two points A and B on a circle, then rotating the coordinate system to determine stresses under different inclinations. Two examples demonstrate using Mohr's circle to find principal stresses, maximum shear stresses, and stresses on a plane inclined at 30 degrees.