
Hip hop as both a musical genre and a culture was formed during the 1970s when block parties became increasingly popular in New York City, particularly among African-American youth residing in the Bronx.[15] At block parties DJs played percussive breaks of popular songs using two turntables and a DJ mixer to be able to play breaks from two copies of the same record, alternating from one to the other and extending the "break". Hip hop's early evolution occurred as sampling technology and drum machines became widely available and affordable. Turntablist techniques such as scratching and beatmatching developed along with the breaks and Jamaican toasting, a chanting vocal style, was used over the beats. Rapping developed as a vocal style in which the artist speaks or chants along rhythmically with an instrumental or synthesized beat. Notable artists at this time include DJ Kool Herc, Grandmaster Flash and The Furious Five, Fab Five Freddy, Marley Marl, Afrika Bambaataa, Kool Moe Dee, Kurtis Blow, Doug E. Fresh, Whodini, Warp 9, The Fat Boys, and Spoonie Gee. The Sugarhill Gang's 1979 song "Rapper's Delight" is widely regarded to be the first hip hop record to gain widespread popularity in the mainstream.[17] The 1980s marked the diversification of hip hop as the genre developed more complex styles.[18] Prior to the 1980s, hip hop music was largely confined within the United States. However, during the 1980s, it began to spread to music scenes in dozens of countries, many of which mixed hip hop with local styles to create new subgenres.

In the 1990s, hip hop began to diversify with other regional styles emerging, such as Southern rap and Atlanta hip hop. At the same time, hip hop continued to be assimilated into other genres of popular music, examples being Neo soul and nu metal. Hip hop became a best-selling pop music genre in the mid-1990s and the top selling music genre by 1999. The popularity of hip hop music continued through the 2000s, with hip hop influences also increasingly finding their way into mainstream pop. The United States also saw the success of regional styles such as crunk, a Southern genre that emphasized the beats and music more than the lyrics. Starting in 2005, sales of hip hop music in the United States began to severely wane. During the mid-2000s, alternative hip hop secured a place in the mainstream, due in part to the crossover success of artists such as OutKast and Kanye West.