It's here once again, February 29th has arrived signifying another leap year.

The purpose of the leap year is actually to keep the seasonal year intact by adding in an extra day every 4 years to make up for the small amount of time we lose every trip around the sun.

James Irving is a teacher at Riverview Collegiate, he explains what would happen if we didn't have a leap year.

"It would actually be surprisingly quick how it would change. You wouldn't see it within a couple of years but over 100 years you would start to see our months fall out of line like we would have March when February used to be and things like that."

The very first concept of a leap year was first introduced by the Roman General Julius Caesar over 2000 years ago, he said every calendar year that was divisible by 4 should be a leap year with no exception. The only problem with that was that it added too many leap years to the calendar resulting in the Julian Calendar separating from the seasonal year at a rate of 1 day per 128 years.

This was not corrected until the Gregorian Calendar took over in 1582.

In the Gregorian Calendar three rules are used to determine leap years. The year must be evenly divisible by four to be a leap year, but if the year can also be evenly divided by 100 it's not a leap year. Finally, if the year can be evenly divided by 400 then it is in fact a leap year.

This would mean that the year 2100 won't be a leap year even though it is evenly divisible by four and 100.