The Poles get about six months of day and six months of darkness due to the tilt of the Earth on its axis.
As a result of this tilt, each pole is slanted towards and away from the Sun for around six months.
When the North Pole is facing the Sun, it has six months of continuous daylight, whereas the South Pole has six months of darkness.
When the South Pole is facing the Sun, it has six months of continuous sunshine, whereas the North Pole has six months of darkness.
Final answer:
The poles experience about six months day and six months night because of the revolution and rotation of the Earth around the Sun.