The Arctic Circle is an imaginary line located at approximately 66.5 degrees north latitude. It marks the southernmost point where the sun can remain continuously above or below the horizon for 24 hours, known as the midnight sun in summer and polar night in winter. This phenomenon occurs because of the tilt of the Earth's axis. The region within the Arctic Circle includes parts of several countries, such as Norway, Sweden, Finland, Russia, Canada, and the United States (specifically, Alaska). The climate is characterized by cold temperatures, ice, and unique ecosystems, including habitats for animals like polar bears and arctic foxes.