A "Solar Day" is the time it takes for the Earth to complete one full rotation on its axis relative to the Sun. This period is approximately 24 hours, which is the basis for our daily timekeeping. It is measured from one solar noon to the next, when the Sun is at its highest point in the sky. The concept of a solar day is important for understanding how we experience time and daylight. It differs slightly from a "sidereal day," which is based on the Earth's rotation relative to distant stars. The difference arises because the Earth is also orbiting the Sun as it spins.