The violin, colloquially known as a fiddle, is a wooden chordophone, and is the smallest, and thus highest-pitched instrument (soprano) in regular use in the violin family. Smaller violin-type instruments exist, including the violino piccolo and the pochette, but these are virtually unused. Most violins have a hollow wooden body, and commonly have four strings, usually tuned in perfect fifths with notes G3, D4, A4, E5, and are most commonly played by drawing a bow across the strings. The violin can also be played by plucking the strings with the fingers (pizzicato) and, in specialized cases, by striking the strings with the wooden side of the bow.

A fiddle is a bowed string musical instrument, most often a violin. It is a colloquial term for the violin, used by players in all genres, including classical music. Although in many cases violins and fiddles are essentially synonymous, the style of the music played may determine specific construction differences between fiddles and classical violins. For example, fiddles may optionally be set up with a bridge with a flatter arch to reduce the range of bow-arm motion needed for techniques such as the double shuffle, a form of bariolage involving rapid alternation between pairs of adjacent strings. To produce a "brighter" tone than the deep tones of gut or synthetic core strings, fiddlers often use steel strings. The fiddle is part of many traditional (folk) styles, which are typically aural traditions—taught "by ear" rather than via written music.