Harmonic motion refers to a type of repetitive movement that occurs in a regular, predictable pattern. This motion is often seen in systems like springs and pendulums, where an object moves back and forth around a central point. The key characteristic of harmonic motion is that the restoring force acting on the object is directly proportional to its displacement from the equilibrium position. A common example of harmonic motion is a swinging pendulum. As it swings, the force of gravity pulls it back toward its resting position, creating a smooth, oscillating movement. This type of motion can be described mathematically using sine and cosine functions, which help predict the position and velocity of the object over time.