Hour (h)
The hour, symbol h, is 60 minutes or 3,600 seconds. It began in ancient times, when people divided the day into 24 parts based on the sun’s movement. This method of dividing the day has remained throughout history. Today, hours organize daily life—jobs, TV, and transport rely on them. The hour is not an SI unit, but it is widely used for convenience and accuracy.
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.