A diatonic harmonica is a single voice instrument and usually has 10 channels, each with one blow and one draw note. It is mainly used in the blues, where the HOHNER Marine Band has played a vital role.
Here is a comparison of the diatonic and chromatic harmonicas. It should help you confirm that you have selected the correct type of harmonica for the style of music and type of sound that interests you. Scroll down the page for details.