This document discusses stability analysis in linear control systems. It defines stability as a system's ability to return to equilibrium after a disturbance or remain bounded for a bounded input. The stability of a closed-loop system can be determined by examining the location of its closed-loop poles in the s-plane - if any poles lie in the right half plane, the system is unstable. The Routh-Hurwitz stability criterion provides a test to determine if all poles lie in the left half plane using the signs of coefficients in an array formed from the characteristic equation.