29th February occurs every 4 years. These are known as leap years. Years that are evenly divisible by 4, such as 2008, are leap years. However, there are some exceptions in century years. A century year, which ends in two zeros, is not a leap year unless it is also evenly divisible by 400.
The additional day was first added to the other 365 days with the introduction of the Julian calendar. This extra day every four years brings the solar year of 365ΒΌ days into line with the calendar year of 365 days.
29th February is the one day of the year on which, traditionally, women can propose to men. It was considered that as the day also had no legal status, it was reasonable to assume that tradition had no status, so women took advantage of this and proposed to the man they wanted to marry. A law once existed in Scotland forbidding a man to refuse a proposal made to him, punishable by a large fine.
A person who is born on 29th February may be called a 'leapling'. In non-leap years they may celebrate their birthday on 28th February or 1st March, but for legal purposes, in Britain, their birthday is 28th February. Statistically, about one in 1,461 births is a leapling and there are an estimated 4.1 million worldwide.