Even though hip-hop has countless shades, colors, splinter wings and internal dissenters, it’s still often spoken about as if it were an undifferentiated mass. Many consider it an outsider phenomenon, even though hip-hop has effectively become the center of pop music. This attitude partly stems from age, race and other things, but mainly from a refusal to see the world as it has become.

This narrow understanding of hip-hop is even more surprising because part of the genre’s brilliance is how it’s moved away from the margins and seeped into the mainstream in unexpected places and ways — providing soundtracks for ads, shilling brands, giving teenagers new slang. Like oxygen, it belongs to everyone.

And then, inevitably, the adopters and interlopers begin to succeed on their own terms, which leads to phenomena like Macklemore & Ryan Lewis’s “Thrift Shop” and Baauer’s “Harlem Shake.” For the last few weeks “Thrift Shop” has been the No. 1 song in the country, according to the Billboard Hot 100, and since the beginning of February “Harlem Shake” — more specifically, the first 30 seconds of it — has been the soundtrack for the latest viral dance-video craze. Both songs have been hovering at or near the top of the iTunes sales chart.