The Eastern Time Zone is a time zone encompassing part or all of 23 states in the eastern part of the United States, parts of eastern Canada, and the state of Quintana Roo in Mexico.
Eastern Standard Time is five hours behind Coordinated Universal Time. Observed during standard time.
Eastern Daylight Time is four hours behind Coordinated Universal Time. Observed during daylight saving time.
On the second Sunday in March, at 2:00 a.m. EST, clocks are advanced to 3:00 a.m. EDT, creating a 23-hour day. On the first Sunday in November, at 2:00 a.m. EDT, clocks are moved back to 1:00 a.m. EST, which results in a 25-hour day. From Wikipedia
