A string is the vibrating element of chordophones such as the guitar, harp, piano (piano wire), and the violin family, that produces sound. Strings are lengths of a flexible material that a musical instrument holds under tension so that they can vibrate freely, but with control.

String is used to tie, bind, or hang other objects. It is also used as a material to make things, such as textiles, and in arts and crafts. String is a simple tool, and its use by humans is known to have been developed tens of thousands of years ago.