The knowledge of change has forced perhaps all living beings of a sense of time, especially human beings.
When people see all around them, they need to express the change in terms of past, present and future.
The most important among them are day and night.

A day is divided in 24 hours, one hour is divided in 60 minutes and One minute is divided in sixty seconds.
The whole period of a day and a night is considered a day in common parlance.

We count such seven days in a sequence with the given names Sunday, Monday, Tuesday, Wednesday, Thursday, Friday and Saturday, which we call a week.

These days form twelve months - January, February, March, April, May, June, July, August, September, October, November and December. And these months form a year.

The History of Time is a facinating story all over the world. There are many calendars prevalent all over the world. Here are few important calendars.

Gregorian Calendar Indian Calendar Early Roman Calendar Julian Calendar Christian Ecclesiastical Calendar Jewish Calendar Islamic Calendar Chinese calendar