The Arctic (Land of the Midnight Sun) is the area around the earth's North Pole while antarctic is in South Pole. It includes parts of Russia, Alaska, Canada, Greenland, Lapland and Svalbard as well as the Arctic Ocean.
The Arctic Circle is one of the five major circles of latitude that mark maps of the Earth.
Everything north of this circle is known as the Arctic, and the zone just to the south of this circle is the Northern Temperate Zone.
This is the parallel of latitude that runs approximately 66.5° north of the Equator. Within the Arctic Circle, the arctic Sun is above the horizon for, at least, 24 continuous hours per year, in conjunction with the arctic's Summer Solstice. Likewise, in conjunction with the arctic's Winter Solstice, the arctic sun will be below the horizon for, at least, 24 continuous hours.
See also: Arctic Ocean