EST/EDT refers to Eastern Standard Time/Eastern Daylight Time. It is a time zone used in parts of North America, including the eastern United States, eastern Canada, and some Caribbean islands. Eastern Standard Time is 5 hours behind Coordinated Universal Time (UTC-5), while Eastern Daylight Time is 4 hours behind Coordinated Universal Time (UTC-4) and is used during the summer months. The time zone is commonly used in financial markets to refer to the opening and closing times of stock exchanges and other trading platforms located in this region.