Eastern Daylight Time (EDT) is a time zone that is four hours behind Coordinated Universal Time (UTC-4). It is observed during the summer months when clocks are set forward by one hour to make better use of daylight. EDT typically begins on the second Sunday in March and ends on the first Sunday in November. EDT is used in several regions, including parts of the United States and Canada. Major cities like New York, Washington, D.C., and Toronto observe this time zone. When EDT is not in effect, these areas switch to Eastern Standard Time (EST), which is UTC-5.