It can be said that it is a kind of rhythm and blues (R&B) fundamentally.
It is a system of the music which applied in early the 1950s to the 1960s, and was developed and made from African Americans' gospel and the blues in the United States.
The music of the black origin of R&B etc. is widely recognized as popular music music, and came to be spontaneously called soul music in music with a thicker gospel color in the 1960s which it reached far and wide, and were developed and expanded.
Although there are also culture nature and art, soul music is public music fundamentally and is a popular song.
There are chord progression of gospel origin, a rhythm with which it assails and which is easy to memorize, a call and response, and which improvisatorial busy feature.
A soul is difficult and also sets drawing a clear boundary line between R&B to a genre division of music, such as genre classification, and a sales chart, etc. of a record store. It is treated as the same thing like a soul/R&B in many cases.
In between the black contemporary that was used in the 1980s, to the soul that there is a violent expression, such as Shout, Burakon is often not the shout, was a possible draw at that point.
It dissociated around the 1990s as implications near the blues by making into a soul the music which a veteran sings.
On the other hand, it came to call R&B the possible song thing of the hit which a youngman sings.