Atomic time is a precise measurement of time based on the vibrations of atoms, specifically the cesium atom. It is defined by the International System of Units (SI) and is used to maintain the accuracy of clocks. Atomic clocks, which utilize this principle, are the most accurate timekeeping devices available, losing only about one second every 30 million years. The standard for atomic time is known as Coordinated Universal Time (UTC), which combines atomic time with astronomical observations to account for variations in the Earth's rotation. This ensures that our timekeeping remains consistent and reliable for various applications, including navigation and telecommunications.