Instruments
String instruments produce sound from vibrating strings. This can occur when a musician plucks the strings with their fingers or a plectrum. Some instruments, like a piano, have keys that, when pressed, pluck the string for them. Other string instruments can be played by hitting or rubbing the strings with a hammer or bow.
String instruments can play different notes by shortening or lengthening the strings. This changes the pitch of the notes that the instrument plays. This can be done by pressing on the strings or tuning the instrument.