A critically damped oscillator is a system that returns to its equilibrium position as quickly as possible without oscillating. This occurs when the damping force is precisely balanced with the system's natural frequency, allowing it to settle down in the shortest time. In practical terms, critically damped systems are often found in devices like shock absorbers and door closers, where smooth and quick return to a resting state is essential. Unlike underdamped systems, which oscillate before settling, or overdamped systems, which take longer to return, critically damped oscillators provide optimal performance in many engineering applications.