How many strings does a standard violin have?

Four, tuned in fifths - G, D, A, E - which is what makes the violin's fingering geometry different from a guitar's tuning in fourths, and why the instrument covers a wide range without moving the hand very far.

The strings pull with a combined tension of around 25 kilograms, all of it pressing down through the bridge onto a thin spruce top. The top survives because of two pieces of hidden carpentry: a bass bar glued underneath to spread the load, and a soundpost, a small dowel wedged between the top and back which is not glued at all - friction alone holds it - and which transmits vibration to the back plate. Move it a millimetre and the instrument sounds different. Italian makers call it the soul.

Whether the old Cremonese instruments are actually better is one of music's touchier arguments. In blind tests, soloists have not reliably distinguished a Stradivarius from a good modern violin, and have sometimes preferred the new one. The results are disputed on their methodology every time they are published.