Revisit some of the predominant trends in music that came to define a mercurial decade, from pop-rap and boy bands to aesthetic sadness and protest anthems. Rap goes the viral pop routeAt the beginning of the 2010s, rap stars had trouble scoring their own No. Dark and dreary pop blows upLana Del Rey helped to usher in a new era of downbeat and dark pop. Karl Walter/Getty ImagesBoth the Weeknd and Del Rey have pivoted since their debuts, with their images becoming more complicated than their indie origins belie. Del Rey, meanwhile, has only burrowed deeper into her niche, crafting intensely personal records that have matured with her listeners.

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