Gravitational locking occurs when a celestial body, like a moon or planet, is in synchronous rotation with another body, meaning it rotates on its axis in the same time it takes to orbit. This results in one side always facing the other body. A well-known example is the relationship between the Earth and its moon, Earth and Moon, where the same lunar hemisphere is always visible from our planet. This phenomenon is caused by gravitational forces that create tidal bulges, which eventually lead to a stable configuration. Over time, the rotation of the smaller body slows down until it matches its orbital period, resulting in gravitational locking.