The string family consists of four instruments, the Violin, the Viola, the Cello, and the Bass. Sound is made by each instrument in the family by plucking with the fingers or rubbing the horse hair bow across a string. Each instrument also comes in a variety of sizes, to fit the size of the student. All younger students should be measured by a music teacher or in a music store to determine the size that suits them. Despite these similarities, there are a few fundamental differences between each member of the family.