A mandolin is a stringed musical instrument. Mandolins have 8 strings, in 4 pairs (or courses). Each pair of strings is tuned in unison, and are a fifth apart from adjacent pairs, giving an identical tuning to a violin (G-D-A-E low-to-high). Unlike a violin, the fingerboard of a mandolin is fretted and it is typically played with a flat pick (a plectrum).

Like the guitar, the mandolin is a poorly sustaining instrument --- a note cannot be maintained for an arbitrary time as with a violin. Its higher pitch makes this problem more severe than with the guitar, and as a result, use of tremolo (rapid picking on a single note) is sometimes used to emulate a sustained note.