A day is the time it takes the Earth to spin around once. It is day time on the side of the Earth that is facing the Sun. When it is night time, that side of the Earth is facing away from the Sun. It takes 24 hours for the Earth to spin once, so that is one day, including the day time and night time.
List of days of the year
|Days of the Week|
|Sunday | Monday | Tuesday | Wednesday | Thursday | Friday | Saturday|
Day for Kids. Kiddle Encyclopedia.