Which is the world's best selling musical instrument?

According to musicians (Bob Dylan, Howard Levy, Bruce Springsteen) and some music experts, the world's best selling musical instrument is the harmonica. It is a musical instrument that is constructed or used for the purpose of making musical sounds (playing notes). In principle, any items (not just harmonicas) which produce sounds can serve as a musical instrument.

The harmonica, known as a French harp or mouth organ, is a free reed wind instrument. It can trace its origins back to 2500 BC where the “free reed” instrument was seen in the traditional Chinese sheng. It is an instrument that has now been used worldwide for centuries in many musical genres, notably the blues, in American folk music, classical music, jazz, country, rock and roll, etc. Because of notes that are readily available on different types of harmonicas, it is an item which has gained great popularity over time. Over one billion harmonicas have currently been sold by the producer Hohner, a musical instrument company founded in 1857.