Hip hop music (also referred to as rap or rap music) is a style of popular music. It is made up of two main components: rapping (MC'ing) and DJing (audio mixing and scratching); along with breakdancing and graffiti (tagging), these are the four elements of hip hop, a cultural movement which began among African Americans and Latinos in New York City in the early 1970s.

Most typically, hip hop music consists of one or more rappers who chant semi-autobiographic tales, often relating to a fictionalized counterpart, in an intensely rhythmic lyrical form, making abundant use of techniques like assonance, alliteration, and rhyme. The rapper is accompanied by an instrumental track, usually referred to as a "beat" because of the emphasis on rhythm, performed by a DJ, a record producer, or one or more instrumentalists. This beat is often created using a sample of the percussion break of another song, usually a funk, rock, or soul recording. In addition to the beat, other sounds are often sampled, synthesized, or performed. Sometimes, a track can be made up of just the beat by itself, as a showcase of the skills of the DJ or producer.

Hip hop arose in New York City when DJs began isolating the percussion break from funk or disco songs. The role of the emcee (MC) arose to introduce the DJ and the music, and to keep the audience excited. The MCs began by speaking between songs, giving exhortations to dance, greetings to audience members, jokes and anecdotes. Eventually, this practice came to be more stylized, and was known as rapping. By 1979, hip hop had become a commercially recorded music genre, and began to enter the American mainstream. It also began its spread across the world. In the 1990s, a form called gangsta rap became a major part of American music, causing significant controversy over lyrics which were perceived as promoting violence, promiscuity, drug use and misogyny. Nevertheless, by the beginning of the 2000s, hip hop was a staple of popular music charts and was being performed in many styles across the world.

Cited from Wikipedia.