What are swollen tonsils or enlarged tonsils? Tonsils are two round lumps that are located in the back of the throat. The purpose of tonsils is to prevent bacteria and viruses from entering the body through the nose or mouth. However, when tonsils become enlarged in adults or children, they can be the cause of certain health conditions. Sep 27, · Tonsillitis most often affects kids and teens, but adults can develop it, too. Tonsillitis is inflammation of the tonsils. The tonsils are two Author: Julie Marks.