A calendar date is a reference to a particular day represented within a calendar system. The calendar date allows the specific day to be identified. The number of days between two dates may be calculated. For example, "25 May 2024" is ten days after "15 May 2024". The date of a particular event depends on the observed time zone. For example, the air attack on Pearl Harbor that began at 7:48 a.m. Hawaiian time on 7 December 1941 took place at 3:18 a.m. Japan Standard Time, 8 December in Japan.
Postal mark of Czechoslovakia dated 13 June 1939
Memorial plaque to John Etty in All Saints' Church, North Street, York, uses dual dating style to record his date of death as "28 of Jan: 170+8/9"
A day is the time period of a full rotation of the Earth with respect to the Sun. On average, this is 24 hours. As a day passes at a given location it experiences morning, noon, afternoon, evening, and night. This daily cycle drives circadian rhythms in many organisms, which are vital to many life processes.
Decimal clock face, made in around the start of the 19th century
Night in art
Image: Midtown Manhattan from Weehawken September 2021 panorama 1
Image: Midtown Manhattan from Weehawken September 2021 panorama 2
