Final answer:
An underdamped system oscillates around equilibrium, a critically damped system returns to equilibrium quickly without oscillating, and an overdamped system moves toward equilibrium more slowly than a critically damped system.
Step-by-step explanation:
With regard to a second-order system, the terms underdamped, critically damped, and overdamped refer to the type of damping present in the system, which affects how the system returns to its equilibrium position after being displaced. An underdamped system is one that moves quickly to equilibrium but oscillates about the equilibrium point as it does so. Critically damped systems move as quickly as possible toward equilibrium without oscillating about the equilibrium. An overdamped system moves more slowly toward equilibrium compared to a critically damped one. This describes the behavior related to the damping factor in oscillatory systems such as those found in mechanical or electrical engineering.