The earth is divided by a number of latitudes and longitudes. Longitudes divide the earth into different time zones. Time zones refer to different places on earth where a uniform time is observed for convenience purpose. Time zones are set up for commercial, social, and legal purposes too. The boundaries of the time zones are irregular since they pass through a number of countries. Each time zone has a division of 15 degrees, i.e. all time zones are 15 degrees away from each other. A country can have more than one time zone passing through it; it entirely depends upon the size and the global location of the country. Countries like United States of America and Russia have multiple time zones because of their huge size. Almost all time zones are linked with the UTC or the Coordinated Universal time. The time zones start from Greenwich, which is in England.
One of the major time zones is EST. EST is the abbreviated form of Eastern Standard Time. It is on the west of the Greenwich Meridian and it goes through 17 states of the United States of America; it also runs though Canada and three countries of South America. Therefore this time zone is used in more than three countries.
Places like Ontario, Quebec observe the Eastern Standard time in Canada whereas places like South Carolina, Connecticut, Vermont, West Virginia, South Carolina, Ohio, Pennsylvania, Massachusetts, New York, New Jersey, New Hampshire, Delaware, Georgia, etc. use EST as their legal time. The Caribbean Islands are a part of this time zone as well.
This time zone is 75 degrees west of Greenwich. Eastern Standard Time is five hours behind Greenwich Mean Time and therefore one can calculate the time difference accordingly. This time zone was ratified in 1915.