Three months were involved in the creation of leap year; February, July and August. In Roman times, the month of February had 30 days. The month of July, named after Julius Caesar had 31 days whereas August had only 29.
When the Emperor Augustus Caesar came into power, his ego demanded that the month of August, which was named after him, have the equal number of days as July. He decided to take away two days from February, add them to August, and from that moment on, leap year came into existence every four years as a result of the adjustment to the calendar.