The Eastern Time Zone (ET) of the Western Hemisphere – also known as North American Eastern Standard Time (NAEST) – is a time zone that falls mostly along the east coast of North America. Its UTC time offset is −5 hrs during standard time and −4 hrs during daylight saving time. The clock time in this zone is based on the mean solar time of the 75th meridian west of the Greenwich Observatory.
In the United States and Canada, this time zone is generally called Eastern Time (ET). Specifically, it is Eastern Standard Time (EST) when observing standard time (winter), and Eastern Daylight Time (EDT) when observing daylight saving time (summer).