A string instrument is a musical instrument that makes sound by vibrating the strings on it. The strings are plucked to produce sounds. Each string has a different frequency. The desired frequency can be obtained by adjusting the tension on the string. A string instrument plays soft notes. The strings on the instrument usually come in many shapes and forms. There are many types of stringed instruments. The most common of these appear in the violin family. The violin is a small, stringed instrument played with a bow, usually made of horse's hair. When the bow is drawn across the strings it creates a vibration. You can select what vibration the bow makes by choosing the note on the fingerboard. It is tuned to G, D, A and E. The viola is a very similar instrument aside from some small differences - it is slightly larger, and is tuned to C, G, D, and A. The cello is a stringed instrument that is played in the bass clef. It is much bigger than the violin, and is also played much differently. The double-bass is bigger still and is the lowest of them all. 