Thanks to Roman Emperors Julius and later Augustus Caesar, and to Pope Gregory XIII, Feb. 29 - Leap Year Day - is our quadrennial bonus day.

Sure, it's not an uppercase holiday with time off and bank closings. But these are 24 hours we didn't have last year and that we won't experience again until 2012.

Through the years, people born Feb. 29 were alternately teased as "babies" and celebrated as oddities. They are hounded with questions about when they celebrate their birthdays in off years. Some speak with horror of doctors who suggest writing Feb. 28 or March 1 on the birth certificates of newborn Leaplings, "just so there won't be any trouble later."

And now, some parents may be moving in the other direction - aiming to give birth on Feb. 29 so their children will have that distinction.

For Raenell Dawn of Oregon, who cofounded the Web site leapyearday.com, the torture began in second grade. The teacher was explaining the leap year concept, and Dawn spoke up about her status.

"The teacher clasped her hands to her chest and said, 'Oh you poor child.' And that day, in recess, the teasing started."

Statistically, the chance of being born Feb. 29 is 1 in 1,461. But when Cynthia Russell of Pennsville, N.J., was told her labor would have to be induced on or after Feb. 28, she opted for the 29th.

"I was already busy on the 28th," Russell said, "And my other daughter's birthday is March 2. So I picked the 29th to create a little time between them. And besides, it makes her special."

The special child, Alexandria Bak, is turning 8 on this, her second birthday. Mother and daughter made frog-shaped lollipops and soap to put in the goodie bags for Alexandria's party tonight. (Frogs leap - get it?)

Alexandria shrugs when asked about why leap years exist. Who cares as long as there is cake?

W.J. Helzlsouer, a lawyer turning 60 on this, his 15th birthday, was one of nine Leaplings born the same day in the only hospital in the small town of Dravosburg, Pa., outside Pittsburgh.

Being a Leaper "has always made me sort of an oddity," says Helzlsouer, who appears on a special Leap Day edition of The Martha Stewart Show today, and is getting a free dinner at his local Morton's Steakhouse tonight.

"What else have you got in life?" he asks.

Dawn of leapyearday.com and her Web partner, Peter Brouwer of Vancouver, British Columbia, expect to spend the day offering explanations.

Leap years were created to keep the calendar (and thereby the seasons) in sync with the Earth's revolutions around the sun. The trip takes 365.2425 days, so the leftover quarter-day from each year is patched into a full day every four years to avoid "seasonal drift."

The Roman Emperor Julius initiated the concept, Augustus tweaked it, and finally Pope Gregory ordered changes that resulted in what we call the Gregorian calendar.

Leaping is not restricted to the solar calendar. The Jewish lunar calendar stockpiles the annual shortage of seconds and adds an entire month seven times over a 19-year cycle, about every three years.

So, in this year of 5768, there will be two months of Adar (I and II).

None of this will make sense to preschoolers, says Dawn, who is turning 48 on this, her 12th birthday.

"Thank goodness there are now more children's books on the subject," she says.

Leapers lament not seeing their precise birth date on every calendar, every year.

And they consistently report problems with getting or renewing driver's licenses, Brouwer says. He has wrangled with Web sites that can't seem to register Feb. 29 as a legitimate birthdate.

"It's very irritating," says Brouwer, who is also a techie. He had success with Microsoft, YouTube and Borders Books. Others, he says indignantly, "just ignored us."

Meanwhile, marketing and sales people nationwide are awakening to the day's potential.

The Philadelphia Wings indoor lacrosse team is giving anyone born Feb. 29 two free tickets to tonight's game against the New York Titans. So, Abington Township Leaper Barbara Milkis, who is 76 today and celebrating her 19th birthday, will be there with grandson Randall Allen, who is 8 and celebrating birthday No. 2.

Morton's Steakhouses in Philadelphia and King of Prussia are giving free dinners to the first 29 Leapers who make reservations. The Papa John's and Domino's pizza chains have giveaways, as do the Ronzoni pasta folks and Boston Market restaurants.

Martha Stewart (an August baby, she) will have only Leap Year Day babies in her studio audience today. Oskar Huber Furniture is offering no interest for four years on purchases made today. Anthony, N.M., hosts a Worldwide Leap Year Festival and Parade.

By the way, Leap Year Day became known as an occasion for a woman to propose marriage to a man at the suggestion of St. Bridget in the fifth century, Dawn says. Don't confuse that with Nov. 15 - Sadie Hawkins Day - which was created in 1937 by Al Capp in his L'il Abner comic strip.

Time magazine says Superman was a Leapling, and the date features in the plot twist of the Gilbert and Sullivan's Pirates of Penzance.

That still leaves one question: On what date will Leapers blow out their candles in 2009?

In the lexicon of Leapers, Brouwer says, those who use Feb. 28 for their off-year birthday celebrations are called Strict Februarians. And Leapers who celebrate the off years on March 1, he says, "are fooling themselves."