Leap Second - Wikipedia - atomic clocks  ## Metadata - Author: **atomic clocks** - Full Title: Leap Second - Wikipedia - Category: #articles - URL: https://en.wikipedia.org/wiki/Leap_second ## Highlights - leap second is a one-second adjustment that is occasionally applied to Coordinated Universal Time (UTC), to accommodate the difference between precise time (International Atomic Time (TAI), as measured by atomic clocks) and imprecise observed solar time (UT1), which varies due to irregularities and long-term slowdown in the Earth's rotation. The UTC time standard, widely used for international timekeeping and as the reference for civil time in most countries, uses TAI and consequently would run ahead of observed solar time unless it is reset to UT1 as needed. The leap second facility exists to provide this adjustment