The year is based off of Earth’s revolution around the sun. 1 year is equal to the amount of time that it takes for Earth to revolve once around the sun.
Revolution of the earth can be defined as the time which is taken by the Earth to move around the sun. The rotates on its own axis and revolves around the sun.
It takes 365 days and 6 hours by the earth to move around the Sun. It moves on a fixed path known as the orbit.
The 6 hours gets added every year and after 4 years it becomes 1 day and forms a leap year which has 366 days.
Natural selection allows nature to chose which species survives. Only the fittest get to pass on their genes. And by fittest i mean the ones that are better adapted to the environment.<span />
