The meaning of DAY is the time of light between one night and the next. How to use day in a sentence. Discover today's unique celebrations, holidays, and observances on National Today. Find out what makes this day special and worth celebrating! DAY definition: the interval of light between two successive nights; the time between sunrise and sunset. See examples of day used in a sentence. 🎉 Browse hundreds of national days, holidays and celebrations. Find today's national days, explore what's coming up this week, and never miss a fun holiday again. A day is the time period of a full rotation of the Earth with respect to the Sun. On average, this is 24 hours (86,400 seconds). As a day passes at a given location it experiences morning, afternoon, evening, and night. This daily cycle drives circadian rhythms in many organisms, which are vital to many life processes. A collection of sequential days is organized into calendars as dates. Day is a fundamental term representing a 24-hour cycle, daylight hours, and specific events or eras. Its widespread use reflects its significance in organizing time and describing experiences. Find out today's date, current time, day of the week, week number, and more. Your complete date and time resource. Day agents run your go-to-market around the clock and bring you the finished work to review, in real time. Built for teams running go-to-market on Claude. Details about today's date with count of days, weeks, and months, Sun and Moon cycles, Zodiac signs and holidays. The official source for National Days. Find a complete list of today& 039;s holidays, unique celebrations, and fun ways to celebrate every day of the year.