Since catapulting to the forefront of pop culture when she was just a teen in the late ’90s, Britney Spears has earned five No. 1s and 13 top 10s on the Billboard Hot 100 – not to mention selling 34 million albums in the U.S., per MRC Data.

But Britney isn’t just one of the biggest artists of the 20th century. She’s also one of the most defining cultural touchstones of our time, having symbolized everything from suburban schoolgirl innocence to bold sexual confidence to resilience and hard-fought freedom.

In honor of Britney Spears’ 40th birthday (Dec. 2), Billboard revisited her extensive catalog of pop classics and came up with our staff picks for Britney Spears’ 40 best songs.