Eastern Standard Time (EST) is a time zone that is 5 hours behind Coordinated Universal Time (UTC-5). It is primarily observed in the eastern part of the United States and parts of Canada. EST is used during the fall and winter months, typically from the first Sunday in November until the second Sunday in March. During the spring and summer months, regions observing EST switch to Eastern Daylight Time (EDT), which is UTC-4. This change helps to make better use of daylight in the evenings. Major cities in the EST zone include New York City, Washington, D.C., and Toronto.