First off let's define R&B.
Rhythm and blues (also known as R&B or RnB) is a popular music genre combining jazz, gospel, and blues influences, first performed by African American artists.
Writer/producer Robert Palmer defined "rhythm & blues as a catchall term referring to any music that was made by and for black Americans."[1] He has used the term R&B as a synonym for jump blues.[2] Lawrence Cohn, author of Nothing but the Blues, writes that rhythm and blues was an umbrella term invented for industry convenience. According to him, the term embraced all black music except classical music and religious music, unless a gospel song sold enough to break into the charts. [3]
This was a small piece of a large article on wikipedia. I would broaden the definition to include not just black Americans but all people who are moved by a strong beat and soulful, heartfelt melodies. Hey, to each their own but it's difficult not to find influence from R&B in any post 1940 music. (minus classical, polka,opera, and death metal).
James Brown, Marvin Gaye, Temptations, Al Green, Sam Cooke, Fats Domino, Ray Charles, Johnny Otis, Big Bill Broonzy, Chubby Checker, Smokey Robinson,.............what's not to like about these icons of R&B music?