As the calendar flipped to Y2K, teen pop ruled music’s roost, with megastars like Britney Spears and *NSYNC dominating the charts. But over the course of the 2000s, a varied pop landscape would emerge, with streetwise hip-hop, emotionally fraught rock, swooning R&B, hook-studded emo, and big-tent pop all getting their moments in the sun—and even coming together in DJ-crafted mash-ups and high-profile collaborations. Pop in the 21st century’s first decade reflected the emergent digital-music era, with the “on shuffle” ideal resulting in radio playlists where Kanye rubbed elbows with The Killers and Kelly Clarkson, or where a hard-hitting Eminem track was bracketed by offerings from Beyoncé and Mariah Carey. That mix of genres and outsize personalities made for an exciting decade that put the party back in pop.