Britney Spears Birthday
Credit: Getty Images; Retna

Happy birthday, Britney Spears! The pop star hits her milestone 30th today, something her global fanbase is sure to appreciate. (She counts 15 million fans on Facebook and another 11.5 million on Twitter!) Take a moment to celebrate her big day by clicking through her transformation—see her rise from her "...Baby One More Time" teen years to full Femme Fatale now.

Tell us: Do you have a favorite Britney song?