Leap Day happens since as part of the Gregorian reform of the Calendar, an extra day was needed to be added since the solar year was really 365 and 1/4 days long. If a leap day wasn't added the seasons will be out of sync with the calendar. Every 4 years we have a leap year except in years that are divisible by 100. If the year is divisible by 400 then we have a leap year. So 2000 was one but 1900 wasn't.
But Gregorian reforms aside, the one reason why leap days and years are of interest is because of a long standing tradition that a woman may propose marriage to a man on these years and on leap day itself, it was ILLEGAL for a man to refuse! A supposed 1288 law promulgated by Queen Margaret of Scotland made it illegal to refuse. The penalties were once so drastic. (Was it death by hanging and quartering? Not really!) A man had to pay 1 pound which was then a huge sum of money. Because the law was so harsh the Queen reduced the penalty to a kiss. The man has give a kiss to the spurned lady.
In the age of gender equality such traditions are now quaint. But bachelors who value their liberty still feel uneasy.
But without these traditions this day would be just any other day. Ho hummm.
Also today leaplings (people who have their birthdays on Feb 29 have double reason to celebrate).Their real birthdays happen only on this day. In common years they either celebrate it on Feb 28 or Mar 1.
So people born in 1968 are just 10 years old! You guys are lucky for 10 is a good age!