If you were looking for the fictional band R.A.P., then you're wrong.
Rap or rap music or OMG RAP MUSIC!!! is a form of music known as the "loud" music by old people who just don't understand.
Rap is listened to by exactly 2,234,234,453,544,345,654,322,225 (2 gazzillon, or something like that) people, and counting.
Rap music started its roots in the 1980's, even though people have been suspicious of Queen, a band who released the stomp-stomp clap beat song, We Are the Champions, and it is known to be early rap/rap-rock (cuz of its solo)