We use various units of time, including seconds, minutes, hours, days, weeks, months, and years, to measure duration and epochs. These units are essential for civil, industrial, and scientific purposes, allowing us to regulate activities, track events, and conduct research.
The basis for modern timekeeping is the 365-day solar calendar, with a leap year every four years. Our clocks are based on the number 60, originating from the Sumerians, with 60 seconds per minute and 60 minutes per hour. Time measurements assign a unique number to an event or interval, and can be tracked using phenomena that undergo regular changes.
Accuracy in specifying time is crucial, and the second is the fundamental unit of time in the International System of Units (SI). Time scales, such as dynamical and atomic time, help us organize events, and Coordinated Universal Time (UTC) serves as the international basis of civil and scientific time. Calendars, like the Gregorian calendar, help us divide time into ordered periods for civil, religious, historical, and scientific purposes.