The Eastern Time Zone (ET) is a time zone encompassing 17 U.S. states in the eastern part of the contiguous United States, parts of eastern Canada, the state of Quintana Roo in Mexico, Panama in Central America and the Caribbean Islands.
Places that use Eastern Standard Time (EST) when observing standard time (autumn/winter) are 5 hours behind Coordinated Universal Time (UTC−05:00).
Eastern Daylight Time (EDT), when observing daylight saving time (spring/summer) is 4 hours behind Coordinated Universal Time (UTC−04:00).
In the northern parts of the time zone, during the second Sunday in March, at 2:00 a.m. EST, clocks are advanced to 3:00 a.m. EDT leaving a one-hour "gap". During the first Sunday in November, at 2:00 a.m. EDT, clocks are moved back to 1:00 a.m. EST, thus "duplicating" one hour. Southern parts of the zone (Panama and the Caribbean) do not observe daylight saving time.