Year (yr)
The year, symbol yr, is the time Earth needs to go around the sun—about 365.242 days. People have tracked years for farming and religion for a long time, creating calendars. The Julian and then the Gregorian calendars made the year’s length more exact by adding leap years. Today, the year is used everywhere for history, science, work, and culture. Years are closely linked to how people see seasons and life’s cycles.
Week (wk)
The week, symbolized by wk, is 7 days long. Its history is rooted in ancient traditions, including Babylonian, Jewish, and Roman customs. The seven-day week originated because of religion and culture, and later became established through Christianity and Islam. Although the week is not based on astronomy, it is now widely used in calendars and daily life. Its long use shows how strong traditions are in setting time.