A guitar is a musical instrument that is typically made from wood, with six strings, although you can also get more strings. This entry is about the acoustic guitar that doesn't require an electronic amplifier to work. Guitars have been around for thousands of years in various forms, and today they are one of the most popular instruments. Acoustic guitars are most often played as a backing instrument. Guitars are typically used in modern folk, pop and rock music, although the electric guitar is more common in modern rock and pop that you hear every day on the radio.