Why do we have day and night?

Day and night occur because the Earth rotates on its axis. As the Earth spins, different parts of the planet face the Sun, experiencing daylight, while the opposite side is in shadow, experiencing night. This rotation takes approximately 24 hours to complete, defining one day. The axis of the Earth is tilted, which also influences the length of days and nights during different times of the year, leading to seasons. This cycle of day and night regulates biological rhythms for most life forms, ensuring periods for activity and rest.