A point on Mohr's circle represents the state of stress in the material at a particular orientation.

The coordinates used in plotting Mohr's circle are not the spatial coordinates x and y that we customarily work with, but rather the coordinates of Mohr's circle are the stresses σ and τ. To determine orientations from Mohr's circle, we must determine angles relative to a reference point, such as the point x, which represents the state of stress on the x face of the stress element. Consequently, it is very important that you label the points as they are plotted.