Since first emerging in New York City in the seventies, hip hop has grown to encompass not just rapping, but an entire lifestyle that consistently incorporates diverse elements of ethnicity, technology, art and urban life. There are four fundamental elements in hip hop: hip hop dance (notably breakdancing), urban inspired art (notably graffiti), DJing and MCing.
For more information, see Hip Hop Slang on The Cardinal Arlingtoncardinal Blog.