Eastern Standard Time (EST) is a time zone that covers the eastern part of North America, including cities such as New York, Washington D.C., Atlanta, and Toronto. The time zone is 5 hours ahead of Coordinated Universal Time (UTC-5). When Daylight Saving Time is in effect, the time zone becomes Eastern Daylight Time (EDT), which is 4 hours ahead of Coordinated Universal Time (UTC-4).
Here is a list of some of the most commonly used time zones:
This is by no means a comprehensive list, as there are many time zones in use around the world.