This document discusses using the Nyquist plot to determine the stability of a control system. It provides an example of a stable system where the Nyquist plot does not encircle the -1 point, indicating no zeros in the right half plane and stability. An unstable example is also given where the plot encircles the -1 point twice, indicating two zeros in the right half plane and instability. The behavior of the Nyquist plot at high frequencies is explained. MATLAB is referenced for generating Nyquist plots from transfer functions.