Question

what is leap year, why it occurs and how?​

Answer 1

Answer:

It takes approximately 365.25 days for Earth to orbit the Sun — a solar year. We usually round the days in a calendar year to 365. To make up for the missing partial day, we add one day to our calendar approximately every four years. ... So, there are 366 days in the year. This is called a leap year.

Leap years happen because a planet's orbit around the Sun (year) and rotation on its axis (day) are not perfectly in line. This is true of almost every other planet in our solar system. Mars, for example, has more leap years than regular years!