The year 2008 has one extra day in it – February 29th. This is because it's what we call 'a leap year'.

Every four years, the year has 366 days in it instead of 365 – but why does this happen? Well, it actually takes the planet Earth 365 days and six hours to revolve completely around the sun. After four years an extra 24 hours have accumulated so an extra day is added to the calendar.

It is called a leap year because hundreds of years ago in England, the extra day wasn't legally recognised. Contracts that were made were apparently not seen as binding on that day. The British just leapt over that day. Therefore a year with 29 days in February is consequently called a leap year and that 29th day is sometimes called Leap Day.

If you are born on 29th February in a leap year, there are difficulties in celebrating your birthday as the day only occurs once every four years. So people tend to celebrate on either 28th February or 1st March every year.

There is a well-known tradition in the UK associated with 29th February, introduced many centuries ago. Women are allowed to break with tradition and propose to their boyfriends on this day.

This all started back in the 5th Century, when a famous Irish saint, Bridget, complained to Saint Patrick, another famous Irish saint, that women had to wait too long for men to propose. According to the legend, Saint Patrick said any females yearning for a proposal could ask their boyfriend to marry them on this additional day in February.

This so-called tradition was even written in law in the 13th Century. Scotland passed a law allowing women to propose to men in a leap year. It was said that if the men refused, they had to pay a fine!

Now in 2008, there are calls for 29th February to become a public holiday. Some people believe that it should be an official day off, because no one gets paid extra for working an extra day in a leap year. For the moment though, the British still have to go to work on this day.