The question intrigues almost all, especially the ones born on this date. This appears rather silly to add a day into the calendar and spoil the sequence and flow of the dates. Actually this is essential because we have to keep the record of Earth’s rotation and revolution around the sun on track.
The Earth takes a total of 365 days and nearly 6 hours to complete a whole year. This means that every year has extra 6 hours spoiling the calendar. To account for this discrepancy, if you like, the calendars are adjusted about every four years by getting a whole new date added to them. February has to take this addition as it already is the shortest month of the year with 28 days normally. Hence we have a special 29th February this very year too.