Why is one of four years on Earth a leap year?

The fact is that the duration of the earth’s day is just over 24 hours. So for the year runs an extra 6 hours. For convenience, it is customary to consider the year equal to 365 days. And once every four years add another day.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.