A fiddle is a bowed string musical instrument, most often a violin or a bass. Fiddle is a colloquial term for the violin, used by players in all genres, including classical music. Although in many cases violin and fiddle 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.