Four-string instruments are musical instruments that have four strings. Examples of four-string instruments include the ukulele, the mandolin, the banjo, and the bass guitar. The ukulele is a small, stringed instrument that originated in Hawaii and is now popular around the world. It is typically tuned to the same notes as the top four strings of a guitar. The mandolin is a stringed instrument that is similar to a lute and is often used in folk music. The banjo is a stringed instrument that is commonly used in bluegrass and country music. The bass guitar is a stringed instrument that is used to provide the low-pitched rhythm in many types of music.