Definition: (DOD) A second of time that is added to or removed from Coordinated Universal Time (UTC) to keep UTC within 0.9 seconds of UT1 (see Universal Time). Leap Seconds are normally introduced at the end of June or December if required. The decision to introduce a Leap Second is announced by the International Time Bureau (Bureau International de l'Heure, or BIH) approximately eight to ten weeks in advance.
See also Coordinated Universal Time.
