About.com indicates that the tragus is located on the outside of the ear. It is the small protuberance of cartilage located outside the ear canal. It has a roundish shape and varies in size from person to person.
According to Wikipedia, the term "tragus" is derived from the Greek word "tragos," which means "goat." This is because the general covering of the tragus' surface is a bunch of hair that resembles the beard of a goat. Since the tragus is facing rearwards, its primary function is to collect sounds coming from behind. The sounds from behind are more delayed compared to the sounds coming from the front, which helps the person's brain identify front and rear sources of sounds.