Day

Day, 24-hour period during which the earth completes one rotation on its axis as it rotates around the sun. The day is divided into 2 equal parts: from midnight (the beginning of the new day) to noon is designated as a.m. and from noon to midnight is p.m. The term day commonly refers to the time that the sun actually shines during the 24-hour period (the term night refers to the time it doesn't shine). The amount of daylight varies greatly in different parts of the world.