Def Jam salute

ROCK, RAP AND RIOT: "Def Jam changed the way our world sounds," says Grammy host LL Cool J, who joined the label as a teen. "Def Jam forever!" Then he introduces a Kendrick Lamar-ImagineDragons collaboration, referencing Def Jam's famed rock-rap fusions of yore. The duet definitely has Taylor dancing, and the crowd on its feet (Jay and Beyonce, Lorde and others in the crowd are clearly into it). Kendrick is on fire. Another standing O.