A mandolin has eight strings, arranged in four pairs, and a rounded wood shell. As part of the chordophone family, the mandolin is a specific kind of lute. The sound of chordophone instruments comes from vibrating strings. The mandolin, and its neighboring mandola and bouzoukis, qualify as citterns because they are plucked with a plectrum like a guitar's pick, rather than played with a bow like a violin.
Mandolins are tuned like violins, since their pairs of strings correlate with the four strings of the smaller instrument. In chordophones, strings made of wire or sinew are suspended between two end points. The distance and tautness between those anchor points determines the tone. Mandolin strings are tuned in unison and differ from the next pair by a fifth of a note. Some variations on the mandolin are the mandola, tuned a fifth lower, the mandobass tuned like an upright bass, and the mandocello, tuned an entire octave below the mandolin.
Many stages of evolution changed the mandolin from an ancient lute to a modern American folk instrument. Mesopotamia originated a hollowed wood bowl with strings called the Oud, meaning "wood". Many European countries adapted this simplest chordophone, adding strings, frets, lengthening or shortening the strings, and changing the body's shape. Fifteenth century Italy saw the rise of the Mandola, Italian for "almond," the direct ancestor of the Mandolin.
Centuries later, Italians brought their beloved instrument to America in the first and second wave of immigration in the 1830s and 1880s, respectively. When the round-backed variety was introduced to the scene, a musician and manufacturer named Orville Gibson made significant changes to modernize the relic. In the early 20th century, as vaudeville and jazz became popular music forms, Gibson remade the mandolin as an American pastime by flattening the back, curving the neck, adding a fingerboard, and other innovations to make it easy to learn. In parlors and theaters across the country, ordinary people gravitated toward the reinvented instrument for evening entertainment. Even with the fall of vaudeville theater in the 30s, mandolins remained popular. Today their unique sound is associated with musical forms as diverse as jazz, country, folk, bluegrass, classical, and even electric rock.