Mumford & Sons is a British folk rock band formed in London in 2007. The band members play acoustic guitar, drums, keyboard instruments, bass guitar, and traditional folk instruments such as banjo, mandolin, and resonator guitar. They began by using bluegrass and folk instrumentation, with the core instruments of acoustic guitar, banjo, piano, and a double bass, played with a rhythmic style based in alternative rock and folk. Mumford & Sons have been described by The Hollywood Reporter and Forbes as a folk rock band.