Violin construction and mechanics four open strings, usually tuned to G, D, A, and E. The strings run from a tailpiece attached to the base, across a wooden bridge, continue towards the neck of the instrument running parallel to the fingerboard, and connect to the pegbox located at the very top of the violin. They are wound around four tuning pegs that are mounted sideways through holes in the pegbox. The bridge helps to hold the strings in place, while the pegs maintain the tension necessary to produce vibration. Strings were first made of sheep's intestines (called "catgut"), stretched, dried and twisted. Contrary to
Musical instrument classification that are rhythmic, a scheme which was probably the first scholarly attempt, while the earlier ones were traditional, folk taxonomies. More usually, instruments are classified according to how the sound is initially produced (regardless of post-processing, i.e., an electric guitar is still a string-instrument regardless of what analog or digital/computational post-processing effects pedals may be used with it). The modern system divides instruments into wind, strings and percussion. It is of Greek origin (in the Hellenistic period, prominent proponents being Nicomachus and Porphyry). The scheme was later expanded by Martin Agricola, who distinguished plucked string instruments, such as guitars, from