Parseltongue is the language of snakes. It is often associated with Dark Magic, although Dumbledore stated that it is not necessarily an evil quality. Those possessing the ability to speak it ("Parselmouths") occur very rarely. People apparently acquire the skill through learning or via a method of xenoglossia, such as through genetic inheritance (or by use of Dark or dangerous Magic). Harry was a Parselmouth until the age of 17. "Harry Potter and the Chamber of Secrets" explains this was because of Voldemort's passing on some of his abilities to Harry the night he tried to kill him. "Deathly Hallows" reveals that a part of Voldemort's soul within Harry grants him this ability, which is later destroyed leaving Harry stripped of the ability.