So what exactly is a leap year and why do we need them? Well, allow us to explain:

WHAT'S A LEAP YEAR?

A leap year is a year when an extra day is added at the end of the month of February. This happens approximately (but NOT every) four years. This applies to anyone who uses the Gregorian calendar - which is pretty much the whole world.

WHY DO WE HAVE LEAP YEARS?

We have a leap year because a standard year is not actually exactly 365 days long - it's 365.2422 days long, so slightly longer than we count in a standard year calendar.

That long number - 365.2422 - is the number of days it takes the planet Earth, on average, to make a full rotation around the sun.

So, an extra day is added onto our shortest month, about once every four years, in order to keep the calendar months in light with their assigned seasons. If we didn't add the day, the wintry month of February would occur during summer.

The concept of the leap year dates back to Julius Caesar and the ancient Roman Empire, when he commissioned scientists to create the Julian calendar in 46 BC.

SO IT HAPPENS EVERY FOUR YEARS?

Well, this may surprise you, but not exactly.

In general, leap years occur every year that is divisible by four. But the first year of a new century is generally NOT a leap year - EXCEPT if that year is a multiple of 400.

For example, 1900 was not a leap year, but 2000 was.

Why? Pope Gregory XIII made up these rules in 1582. Adding one day to the calendar every four years still puts us just a smidge too far ahead of the season, so we use the calendar system he created to this day.

IS THIS REALLY HOW THE CALENDAR HAS TO WORK?

Not necessarily. Scientists have long tried to get rid of leap years and simplify the calendar.

Most recently, two professors at Johns Hopkins University, Richard Conn Henry and Steve Hanke, proposed a new system that would keep each date on the same day of the week year after the year (imagine never having to buy a new calendar!).

Under the Henry-Hanke model, most years would be 364 days long, and an extra week would be tacked on to the end of December about every six years.
Can get an extra day of rides on February's monthly pass this year. Apartment dwellers receive an added day for their month's rent. And auto salespeople have an extra day to build up their monthly total.
The 29th day added to February - Leap Day - brings a smidgen of a financial boost for some consumers and slight adjustments for businesses that rely on daily sales and workers who are paid by the hour.

But for businesses in a global economy, the effects of the extra day are fairly insignificant, especially as hourly-based manufacturing jobs have decreased and more people are paid an annual salary, experts said.
"For most businesses (Leap Day) was never a big deal and absolutely over time has diminished," said Ken Goldstein, an economist with The Conference Board, a nonprofit business research association.
Leap Year has been around since the days of Julius Caesar. It is necessary to make up for the fact that the Earth's orbit takes a little longer than 365 days to travel around the sun. Feb. 29 is added to the calendar every four years, except for century years not evenly divisible by 400.
Various traditions have sprung up for Leap Day over the years - it was once known as a day when women could propose marriage to men.
Larry Lubell, president at Urban Insurance Agency in Chicago, said February is usually a tough month for his business, and he's glad to have an extra 24 hours to generate revenue. Wednesday "will diminish the negative effect the month usually has," he said.
Lubell said that his company, which sells insurance policies, usually takes in about $15,000 less in February than other months. Leap Day figures to cut that shortfall in half, he said.
For auto dealerships and hotels, Feb. 29 represents an additional opportunity to sell cars and book rooms. But because it falls on a Wednesday, this year's Leap Day will be less of a bonus than it could be, they said.
It would be better if Feb. 29 fell on a Saturday, when the car dealerships tend to see the most business, said Gene Storm, general manager of Fletcher Jones Honda in Chicago.
"The way the car business works is I can sell zero cars one day but then seven on the next," Storm said. "But in general, Wednesday is not going to be dramatic."
An extra Wednesday in the month also will be less than a boon for hotels, where weekends are when business booms.
"It's just an extra day," said Jewel Ritchie, manager of the Hotel Felix in downtown Chicago.
Some businesses plan to make small changes. Richard Dux, owner of a downtown Chicago Subway restaurant, said his February expenses have to be adjusted for the extra day because most of his workers are on hourly wages.
He said the additional day accounts for about 90 more working hours and will cost him an additional $70 in utilities.
But Dux, like other business owners, say that's not a big deal.
"It's a short-term phenomenon," said Sebastien Gay, economics professor at the University of Chicago. "If there are losses, (businesses) will recover in the next month."
For many businesses, changes in the weather each year will have a much bigger effect than an extra day in February.
Joan Schermerhorn, property manager at Evanston, Ill-based Schermerhorn & Co., whose company manages about 90 rental properties, said the savings this year on heat and snow removal are much larger than anything to do with leap year.
"We look more at the big picture," she said.