How is there a Day and a Night ?

As the earth travels around the sun, so it spins on its own axis.
In 24 hours it takes to spin on its axis is called a ‘day’ but , of course , this includes the night hours , too. And night – time varies with the seasons and also with the latitude.
At the Equator it always lasts twelve hours , and , as we get towards the Poles the duration varies until, at the Poles themselves, the nights are six months long!