A mandolin (Italian: mandolino pronounced [mandoˈliːno]; literally "small mandola") is a musical instrument in the lute family and is usually plucked with a plectrum or "pick". It commonly has <answer>four</answer> courses of doubled metal strings tuned in unison (8 strings), although five (10 strings) and six (12 strings) course versions also exist. The courses are normally tuned in a succession of perfect fifths. It is the soprano member of a family that includes the mandola, octave mandolin, mandocello and mandobass.
How many courses does a mandolin commonly have? 
four