When 2003 wrapped up, the songs that ruled the year-end Billboard charts were a mix of rap (“In Da Club” by 50 Cent, taking the top spot), sexy R&B (“Ignition” by the now ignominious R. Kelly), and rock acts that passed as the new adult contemporary (3 Doors Down, Matchbox Twenty). But left of the dial, there was a revolution happening—one that would lead to a new generation of arena bands and have mainstream cultural impact on sound and style. Here are some of the big bands and movements that shook things up two decades ago and whose influence is still being felt today.