Britney Spears’ good-girl-gone-bad growl defined the early 21st century’s pop landscape. She was the sultry heart of Max Martin’s grandiose productions, transformed the sparse “Everytime” into a chilly portrait of loneliness, and added a playful sexiness to Bloodshy & Avant’s spy-movie fantasia “Toxic.” This collection chronicles Spears’ unstoppable run of early singles—including her late-’90s hip-shaking debut “...Baby One More Time,” her zeitgeist-defining, beat-heavy tangles with fellow pop heavyweights The Neptunes and Madonna, and a defiant cover of Bobby Brown’s gotta-be-me broadside “My Prerogative.”