Though it’s second fiddle in digital and physical sales to rock and pop, hip-hop has long been the most popular genre on music streaming services. BuzzFeed News spoke to music industry experts to find out why.

Earlier this year, on Valentine’s Day, much of the internet was enamored of Drake. The Toronto rapper’s commercial mixtape, If You’re Reading This It’s Too Late, which had been released with little warning two nights before, was played more than 6.8 million times on Spotify, the world’s largest music streaming service, more than doubling the previous single-day streaming record. Like a capricious lover, however, that same record would soon move on to another. Almost exactly one month after Drake’s mixtape, and a week ahead of schedule, Kendrick Lamar crashed streaming servers with a surprise release of his own — his second major-label album, To Pimp a Butterfly, which demolished the record set by If You’re Reading This by racking up an unheard of 9.6 million streams on its first full day of release.

These twin high-water marks, set by two of hip-hop’s most dynamic figures (andoccasional rivals), say a lot about the state of the genre, which is flourishing after a relatively fallow 2014. But they also say a lot about the state of streaming, which is not only distinguished from other music platforms in that it’s growing rapidly, but in that the type of music that is driving its growth is rap and R&B.

According to Nielsen Music, a plurality — 29% — of all on-demand streaming in 2014 was of hip-hop and R&B. This includes activity on services like Spotify, YouTube, Rdio, and Rhapsody, but not Pandora or SoundCloud. Hip-hop and R&B’s share of streaming put the genre ahead of rock (25%), pop (21%), EDM (7%), and country (6%). And data provided by Nielsen to BuzzFeed News shows that the trend held for the first quarter of 2015, with hip-hop claiming a 25% share of streaming, compared to 23% for rock and 20% for pop.

Over the past six months, four of the top five most streamed albums on Spotify globally belonged to hip-hop (Drake, Lamar, J. Cole’s 2014 Forest Hills Drive, and Big Sean’s Dark Sky Paradise), with only One Direction’s Fourpreventing a sweep. And last month, the Spotify record for most streamed song in a single week went to the rapper Wiz Khalifa, whose hit “See You Again” featuring Charlie Puth received 21.9 million plays from April 6–12.

Hip-hop’s lead in streaming is remarkable, considering that the genre has historically lagged behind rock and pop in other metrics used by the music industry as barometers of success. When it comes to album sales, for instance, hip-hop and R&B was still a distant second to rock in 2014, accounting for 14% of sales compared to rock’s 33%, according to Nielsen Music. In song downloads, hip-hop and R&B came in third place behind both rock and pop.

As the music industry has shifted to a more streaming-focused model, with both physical and digital music sales continuing to decline, there are signs that hip-hop artists are reaping the benefit. More than a third of the 14 albums to top the Billboard 200 this year, which last November began to include streams as a factor, came from the hip-hop category, including the aforementioned albums by Drake, Lamar, and Big Sean, plus theEmpire soundtrack and Wale’s The Album About Nothing.

“These artists are doing phenomenally well,” Dave Bakula, SVP of industry insights at Nielsen, told BuzzFeed News. “And it’s something we’ve seen for as long as we’ve been tracking [streaming] — R&B/hip-hop really sets itself apart.”

Of course, the million-dollar question is: Why? It’s not easy to say, conclusively. Unlike, say, vinyl, which is today marketed toward older consumers and leans heavily on the classics (4 out of 10 of the top-selling vinyl albums last year were released before 1985), streaming services have long been billed as genre-agnostic musical utopias: all of the music, all of the time. To explain how hip-hop and R&B came to rule such a platform, we talked to industry experts and came away with three theories.

The Youths

The first and most obvious answer has to do with age. Streaming is the youngest of the platforms and, as with most nascent technologies, its user base is similarly young. According to a study by GMI Market Research provided to BuzzFeed News, the average age of users of major music platforms is as follows: Spotify, 28; Pandora, 32; iTunes, 34; SiriusXM, 42; terrestrial radio, 43.

“If you’re 18 years old, you probably don’t have any memory of purchasing music via download or physical product,” said Ken Parks, chief content officer at Spotify. “But you probably do spend a lot of time listening to music on platforms like ours or YouTube.”

From Will Smith to Rae Sremmurd, hip-hop has always been fueled and supported by young people, so it makes sense that a platform with a young user base would see a lot of activity in that genre. “Many 18- to 24-year-olds, which is really our core audience, eat, sleep, and breathe hip-hop,” said Parks. So who’s streaming all of that Wiz Khalifa? Probably not your mom.

Mixtape Culture

Hip-hop, more than any other genre, has a strong tradition of free music. Years before the rise of ad-supported, on-demand streaming in America, rappers big and small were keeping mixtape sites like Datpiff and LiveMixtapes flush with quality content at no cost. When Spotify arrived in 2011 with the promise of making all music available for free, it’s easy to imagine hip-hop fans among its earliest and most avid supporters. “People our age come from an era where you can just go to a mixtape website and download everything for free, so that’s just what we’re used to,” said Tyler, the Creator, whose April album, Cherry Bomb, was the most streamed album on Spotify the week of its release. “Hip-hop fans want the shit right then and there or they’ll download it somewhere else for free. They’re like, ‘What the fuck do I look like buyin’ it?’”

It’s worth remembering that Drake’s If You’re Reading This It’s Too Late mixtape broke on-demand streaming records only after being pulled from traditional mixtape destinations like SoundCloud and LiveMixtapes.

Social Media Behavior

The portability of links to songs on YouTube or Spotify means it’s much easier to share music than ever before, and activity on streaming services often follows social media conversations. According to an unpublished “Music 360” study by Nielsen provided to BuzzFeed News, hip-hop and EDM fans are the most likely to talk about music with friends, including on social media. In a survey of over 2,500 music listeners, 27% of hip-hop fans strongly agreed with the statement “I often discuss music with my friends,” compared to 28% of EDM fans, 21% of rock fans, and 17% of pop/top 40 fans. “I think the social nature of the fan base is a factor here,” said Bakula.

Nielsen’s study of hip-hop fans jibes with earlier research about African-Americans and social media use. A 2014 study by the Pew Research Center found that fully 96% of black Americans between 18 and 29 use social networking sites, compared with 90% of white Americans in the same age group. Smartphone ownership among 18- to 29-year-olds showed a similar gap: 85% of black respondents said they owned a smartphone compared to 79% of white ones.

Among the many ways that the rise of streaming is disrupting the business and culture of music, one of the most significant may be upending paradigms of access and visibility. Originally conceived as the defiant music of outsiders, hip-hop, now more than ever, is poised to become the default. If streaming is the future, than, for now at least, the Drakes and the Kendricks, and the J. Coles of the world are its heirs.