What does Earth do to cause night and day?

Earth rotates on its axis, causing the cycle of night and day.

As Earth spins, different parts of its surface face the Sun. The side facing the Sun experiences daylight, while the side turned away lies in darkness. Because Earth is spherical, the boundary between the illuminated and dark halves moves across the planet, producing sunrise and sunset as locations rotate into and out of sunlight.

Earth spins eastward and completes one rotation relative to the Sun in an average solar day of about 24 hours. Its rotation is also why the Sun, Moon, and stars appear to move across the sky from east to west. The objects are not normally circling Earth each day; their apparent daily motion is largely an effect of our planet turning.

A common mix-up is confusing rotation with revolution. Rotation means spinning around an axis. Revolution means orbiting another body: Earth revolves around the Sun once every year, or about 365.25 days. Earth’s axial tilt is responsible for the seasons, not the basic alternation of night and day. At the poles, this geometry can produce unusually long periods of daylight or darkness.