Daytime

Daytime or day as observed on Earth is the period of the day during which a given location experiences natural illumination from direct sunlight. Daytime occurs when the Sun appears above the local horizon, that is, anywhere on the globe's hemisphere facing the Sun. In direct sunlight the movement of the sun can be recorded and observed using a sundial that casts a shadow that slowly moves during the day. Other planets and natural satellites that rotate relative to a luminous primary body, such as a local star, also experience daytime, but this article primarily discusses daytime on Earth.

Very broadly, most humans tend to be awake during some of the daytime period at their location, and asleep during some of the night period.

Approximately half of Earth is illuminated at any time by the Sun.^[1]

An approximation to the monthly change can be obtained from the rule of twelfths.^[2]

• Daylight saving time
• Solar eclipse
• Sunrise equation
• Sunshine duration