Harmonic motion refers to the repetitive movement of an object around an equilibrium position, often described by a sine or cosine function. This type of motion is commonly observed in systems like pendulums and springs, where the restoring force is directly proportional to the displacement from the equilibrium position. In harmonic motion, the object oscillates back and forth, creating a smooth and predictable pattern. The key characteristics include amplitude, frequency, and period, which define the motion's extent, speed, and duration. Understanding harmonic motion is essential in various fields, including engineering and music.