Earth's polar regions are the areas of the globe surrounding the poles, north of the Arctic circle, or south of the Antarctic Circle. They are characterised by the polar climate, extremely cold temperatures, heavy glaciation, and extreme variations in daylight hours, with 24 hour daylight in summer (the midnight sun), and permanent darkness at mid-winter. The North Pole and South Pole being the centres, these regions are dominated by the polar ice caps, resting respectively on ocean and the continent of Antartica.
There are many settlements in Earth's north polar regions, but none except for scientific bases in the south polar regions, which are colder than the northern polar regions.
Other planets and natural satellites in the solar system have interesting quirks about their polar regions. Earth's Moon is thought to contain substantial deposits of ice in deep craters in its polar regions, which never see direct sunlight. Mars, like Earth, has polar caps, but unlike Earth's icy caps they consist mostly of carbon dioxide. On Uranus, meanwhile, the extreme tilt of the planet's axis leads to the unique situation during the Uranian year of first one pole and then the other pointing almost directly at the Sun.
See also: geographical pole, North Pole, South Pole, Antarctica ecozone