Depeche Mode will forever be '80s icons thanks to their role in helping invent synth-pop as we know it. But unlike so many of their peers, they've remained both active and relevant. From their earliest days with Vince Clarke (before he left for Yaz, then Erasure), Depeche Mode took a spindly, synth-pop sound and filled it out with touches of techno, industrial, Americana and modern rock. Principal songwriter Martin Gore and his bandmates fuse classic pop songcraft with productions that keep pace with advances in music technology; lead singer Dave Gahan's dramatic delivery, meanwhile, has helped their songs of loss and redemption become pop-culture touchstones, covered by everyone from Tori Amos to Marilyn Manson. It's easy to chart the overall arc of the band's career, from its minimalist, electro-pop beginnings to the swelling pop yearning of Music for the Masses and on to the dark extravagance of albums like Violator and Exciter. But an abundance of alternate versions and remixes has produced a messy canon. For many fans, that's half the fun: Depeche Mode's B-sides make for a fascinating alternative history of these alt-rock heroes.