Your ankle connects your lower leg to your foot. The ankle is a joint that bends and swivels.
The ankle is actually a fairly complicated part of your body, officially including three separate joints that make it possible to bend your legs, jump, run, and walk. The major bone in your ankle is called a talus, and it's the one at the very top of your foot. In Old English, it was ancleow, from a root word meaning "to bend," a root it shares with the word angle.