Do you know why January 1 as First day of the year ?

THE HISTORY BEHIND JANUARY 1 AND APRIL 1

            Everyone knows January 1 as very first day of the year. But few only know that before 1564 April 1 was the first day of the year.

            This change is made to establish a universally accepted calendar called Gregorian calendar or Western Calendar. And the people who celebrated the 1^st of April as New Year were called as Foolish by the British people and the day was popularly known as the April fool’s Day.

            During this change over the calendar system of some countries some days has to be omitted. This omission is made to it did not correctly reflect the tropical year or solar year marked by Earth's revolution around the Sun. To get back in step with astronomical reality, a number of days were dropped in the new calendar, creating irregular months with only 18 days and odd dates like February 30.

                  Like UK some other countries also dropped some days and few of them are listed below.

Year	Country	Number of days dropped
1582	France (most areas) Italy Poland Portugal Spain	10 days
1583	Austria Germany (Catholic states)	10 days
1587	Hungary	10 days
1610	Germany (Prussia)	10 days
1752	Canada (most areas) United Kingdom (and colonies) United States (most areas)	11 days
1872/1873	Japan	12 days
1911/1912	China	12 days
1916	Bulgaria	13 days
1918	Estonia Russia	13 days
1923	Greece	13 days
1926/1927	Turkey	13 days

           

For more details http://en.wikipedia.org/wiki/New_Year