A week is a period of seven days, the fundamental unit we use to organize our lives beyond the daily rhythm of sunrise and sunset. The week gives structure to everything from school schedules to work routines to when your favorite TV show airs.

The seven-day week is ancient, dating back thousands of years. Many languages still name their weekdays after celestial bodies. In English, Sunday and Monday clearly refer to the Sun and Moon, while the other days come from Norse gods who corresponded to Roman deities.

Most weeks follow a pattern: five days of school or work (the weekdays), followed by a two-day weekend for rest and activities. When someone asks “How was your week?” they usually mean the seven days since the last weekend.

The word appears in many common phrases. Something happening this week means sometime during the current seven-day stretch. If you go somewhere once a week, you go every seven days. A week from today means seven days in the future. And when someone says “a week ago last Tuesday,” they mean the Tuesday of the previous week, not the most recent one.

Unlike months, which vary from 28 to 31 days, weeks never change length. This consistency makes them reliable for planning, whether you're counting down the weeks until summer vacation or tracking how many weeks you've practiced piano.