The violin is a stringed musical instrument comprising four strings tuned a fifth apart. It is the smallest and highest-tuned member of the violin family of string instruments, which also includes the viola, cello and double bass. The lowest string (and hence the lowest note) is the G just below middle C, then in ascending order D, A and E. Sheet music for a violin almost always uses the G clef (treble clef). To get the best possible sound from the instrument each string must be made a different thickness.