She Against the Music: Britney Spears' Biggest '00s Hits

Just like the '90s didn't really start for some until Nirvana released Nevermind, one could argue that pop's new millennium really started in 1999, when Britney Spears released her landmark debut ...Baby One More Time. Almost overnight, kids and teens (and even their parents) couldn't stop talking about the 18-year-old blonde bombshell from Kentwood, Louisiana with a unique voice and an in-your-face style.

But 20 years later, it's clear that Britney wasn't just an act for one generation - she's made a career out of pursuing pop perfection. With that in mind, here's a look at some of her biggest (and best) moments of the first decade of that new millennium.

"Oops!...I Did It Again"

Indeed she did! Britney's second album Oops!...I Did It Again, released in 2000, featured pop earworms like the movie-star ballad "Lucky," the empowering "Stronger" and even a cover of The Rolling Stones' "(I Can't Get No) Satisfaction." But it's the title track that gets the blood pumping most, thanks to its killer beat (quite similar to "...Baby One More Time") and a rollicking melody. Of course, that iconic performance at the MTV Video Music Awards made this a pretty memorable tune, too.

"I'm a Slave 4 U"

While Swedish hitmaker Max Martin was the writer/producer of Britney's early work, "I'm a Slave 4 U" was the brainchild of Pharrell Williams and Chad Hugo, better known as The Neptunes. This sensuous, funky beat (originally intended for Janet Jackson!) became the biggest of Britney's hits from third album Britney (2001). And once again, it accompanied a killer live appearance at the VMAs - you know, the one with the python?

"Toxic"

Nobody wants to sound dramatic, but 2003's "Toxic" may be the best pop song of all time. Can you believe Brit's record company was picking between two other songs as the second single from In the Zone? Those strings! That guitar! That beat! We're addicted all over again, and so is everyone else: it's her most-streamed track.

Read More: Britney Spears' "Toxic" Video: 3 Fiercest Scenes

"Gimme More"

Three words changed music forever: "it's Britney, bitch." With a new brunette look and some shake-ups in her personal life (including a divorce from dancer Kevin Federline and a series of struggles that caused millions to cry "leave Britney alone!"), 2007's Blackout was a bit of a departure from her previous work, helping pave the way to the sound of pop in the next decade. And "Gimme More" was the song that kicked it off back in 2007, becoming her fifth career Top 10 hit.

"Womanizer"

After the struggles of her last album - Blackout "only" reached No. 2 on the U.S. album charts after four straight chart-toppers - sixth album Circus (2008) was a bit of a comeback for Brit, topping the pop charts once more and, with "Womanizer," delivering her first No. 1 single since "...Baby One More Time." As songs like "Womanizer," "Circus" and "If You Seek Amy" (sound it out!) proved, a woman's place was on the dance floor.

Bonus Track: "3"

Britney closed out the decade with her second greatest hits record, 2009's The Singles Collection. The token new track, "3," was an ode to...how do we put this delicately?...having fun with two other people. With "3," Britney became the first artist to debut at No. 1 in three years. We can't say if "3" is better than one, but it sure comes close!