Types of Harmonica
Harmonicas are generally classified in three basic types
Diatonic, Chromatic and Tremolo.
The diatonic harmonica is the most common harmonica. It’s the one you will most likely find lying around someone’s home.
Diatonic harmonicas are compact, simple, and most commonly have 10 holes . There are 12 basic keys in music. The diatonic, though capable of playing in multiple keys, focuses on playing in one key – one of the reasons they’re so easy to play. You can buy diatonic harmonicas tuned to each of those 12 keys, but beginners are often recommended to start with a harmonica in the key of C.
Bigger than the 12-hole chromatic, this has an extra octave below middle C and demands a lot of practice before you can gain familiarity with its full range.