EDT, or Eastern Daylight Time, is a time zone that is used in the eastern part of the United States and Canada during the summer months. It is four hours behind Coordinated Universal Time (UTC-4). EDT begins on the second Sunday in March and ends on the first Sunday in November, when clocks are set back one hour to Eastern Standard Time (EST). This time zone is observed in major cities such as New York, Washington D.C., and Toronto. The shift to EDT helps to make better use of daylight during the longer days of summer, allowing for more daylight in the evenings.