International Atomic Time (TAI, from the French name "temps atomique international") is a high-precision atomic coordinate time standard based on the notional passage of proper time on Earth's geoid.
International Atomic Time (TAI, from the French name "temps atomique international") is a high-precision atomic coordinate time standard based on the notional passage of proper time on Earth's geoid. It is the basis for Coordinated Universal Time (UTC), which is used for civil timekeeping all over the Earth's surface, and for Terrestrial Time, which is used for astronomical calculations. Since 30 June 2012 when the last leap second was added, TAI has been exactly 35 seconds ahead of UTC. The 35 seconds results from the initial difference of 10 seconds at the start of 1972, plus 25 leap seconds in UTC since 1972.
More information on the topic can be located at its Wikipedia page.
