Rock music is a broad genre of popular music that originated as "rock and roll" in the US in the late 1940s and early 1950s, developing into a range of different styles in the mid-1960s and later, particularly in the US and UK. This style of music drew directly from the rhythm and blues genres of African-American music and from country music. Rock also drew strongly from a number of other genres such as electric blues and folk, and incorporated influences from jazz, classical, and other musical styles. Rock music has centered on the electric guitar, usually as part of a rock group with electric bass guitar, drums, and one or more singers. Usually, rock is song-based music, but the genre has become extremely diverse. Like pop music, lyrics often stress romantic love but also address a wide variety of other themes that are frequently social or political. Rock was the most popular genre of music in the US and much of the Western world from the 1950s to the 2010s.