Antarctica is the name given to the southern polar region of the earth.
There are two main theories concerning the nature and extent of Antarctica. The first and most widely accepted theory says that Antarctica is a portion of ice surrounding the known Earth, and that in its end there is a huge wall of ice (with different sizes depending on the subtheory) which has yet to be fully explored. The second theory says that the center of the earth's surface is the point where the Equator and the Prime Meridian meet, and therefore Antarctica is a distinct continent located at the South.
Below are images of the two flat earth geographic models, which convey the different concepts of Antarctica within flat earth theory: