Antarctica is a vast ice sheet. The continent is larger than the United States of America, and has enough ice to raise global sea levels by ~58 m if it all melted. It is extremely cold, with very little surface melt.
However, it is changing rapidly. Parts of West Antarctica are grounded well below sea level, which can act to destabliise the ice sheet. Warm ocean currents are able to melt ice shelves from below, and cause a retreat of the grounding line of tidewater glaciers. These articles outline how Antarctica is changing.