The violin (Italian: Ilviolino) is a stringed instrument. There are always four strings. The sound is produced by the friction between the string and the bow. The violin is composed of more than 32 parts. The violin body (singing box) is about 35.5 cm long and is made of curved panels, back panels and side panels. The top is usually made of spruce, which has a softer texture; the back and side panels are made of maple or mahogany, which has a harder texture. The headstock and neck are made of solid maple, and the fingerboard is made of ebony. The violin is widely spread all over the world and is the most important instrument in the string section of modern orchestras. It occupies a very important position in instrumental music and is the backbone of the modern symphony orchestra. It is also a solo instrument with difficult performance skills. It is also known as the three major musical instruments in the world along with the piano and classical guitar. Literary works with the violin as the background include "Summer Dreams", "Secret", "Violin Whispers", etc.