A. On average, the Earth takes 23 hours and 56 minutes (not 24 hours) to rotate once on its axis.

Q. So why don't we have to change our clocks every now and then to correct the time?

A. Because the Earth goes around the sun about once every 365.25 days. That adds a revolution per year. So,
24 hours * 60 minutes / 365.25 days = 3.94 minutes

This makes up the difference.

The real reason you don't have to change your watch all the time is that it was designed to work. I mean, who'd design a watch that had 23 hours and 56 minutes per day?

People everywhere are liars.
I've been asking people all day what time it is, and everyone has given me a different answer.