Pop rap is a genre of music fusing the rhythm-based lyricism of hip-hop with pop's preference for melodic vocals, catchy hooks, and occasional rap-singing on pop-like productions and structure, as well as samples of various popular songs. This genre gained mainstream popularity during the 1990s, though the influences and roots of pop rap can trace back to late-1980s hip-hop artists such as Run-DMC, LL Cool J, and Beastie Boys.