Nicknamed Mouth organ, Blues Harp, Tin sandwich, Mississippi Saxophone, the diatonic harmonica is by far the most played and sold harmonica in the world. Of course, it is also much more affordable than his big brothers the chromatic, the bass, and the orchestral harmonica.

At the same time, it is much more versatile than the Tremolo or Octave harmonica and can take you further than very simple folk melodies.

The diatonic harmonica is a 10-hole harmonica with dual reed plates. The top reed plate produces the blow notes whereas the bottom reed plate creates the draw notes. This way you can naturally play 20 notes by just blowing or drawing through your harmonica. But the diatonic harmonica has something up its sleeve.

By changing the way you inhale or exhale and shaping the airflow you can produce up to 18 more notes! In the end, the diatonic harmonica using bends and overbends is a fully fledge chromatic instrument in the hand of a good player!

This is especially true of the top-of-the-line models such as the Harmo Custom Shop model with Ultimate setup where each reed is manually optimized to make each bend and overbend much more responsive and easily available than on standard models such as the Hohner Special 20.

The diatonic harmonica is primarily used in Blues where artists like Sonny Boy Williamson, Little Walter, or Big Walter Horton forged its sound.

It's also been very popular in Folk music with Bob Dylan, Crosby, Stills, Nash, and Tony Joe White who performed in Woodstock.

Since the 1980s the diatonic harp has also been seen more often in Celtic music, Country Music, Bluegrass, and Jazz with some players developing insane bebop chops.

There is a plethora of diatonic harmonica models made by each major manufacturer. Here is a shortlist of the most popular ones:

- Hohner diatonic harmonicas: Special 20 - plastic comb brass reeds, Marine Band - Agglomerate wood brass reeds, Golden Melody - plastic comb brass reeds, Rocket - plastic comb brass reeds, Marine band Deluxe - pear wood brass reeds, Crossover - Bamboo comb brass reeds

- Lee Oskar harmonicas: There is only one model for Lee Oskar and it is a plastic comb brass reeds.

- Suzuki diatonic harmonicas: Bluesmaster - plastic comb brass reeds, Promaster - Aluminum comb phosphore bronze reeds, Pure Harp - rosewood combphosphore bronze reeds, Fabulous - Brass comb phosphore bronze reeds, Manji - composite comb phosophore bronze reeds

- Seydel harmonicas: Session standard - plastic comb brass reeds, Session Steel - plastic comb stainless steel reeds, 1847 - wood or plastic comb and stainless steel reeds

- Harmo harmonicas: Polar - abs comb phosphore bronze reeds, Torpedo abs comb phosphore bronze reeds with manual optimization for overblows, Harmo Custom Shop harmonica - Walnut, Maple, Aluminum, Brass or plastic comb combined with phosphor bronze reeds and wood, aluminum or brass covers.