The USA. has an additional reason to party: It's Miley Cyrus's birthday. The teen pop superstar -- born Destiny Hope Cyrus, known to many as Hannah Montana -- turns 18 today, so we're taking a look back at her life so far, her major milestones and her transformation into one of the most popular girls in the world. So join the birthday party. After all, Miley has been going at it all November. As she told Access Hollywood, "I have a birthday month ... I do the whole month of November. Thanksgiving, cake -- [It's] all about me on Thanksgiving!"