The Meaning of the Name:
Rhythm & Blues is a term used to describe the blues-influenced form of music predominantly performed by African-Americans since the late 1930s. The term 'Rhythm and Blues' was first introduced in the late 1940s: it was created for use in musical marketing by Billboard magazine. In 1949, Billboard reporter Jerry Wexler (who later went on to become a music producer), created the phrase to designate the upbeat popular music performed by African American artists that combined jazz and blues.
The Reason for the Name:
The "Rhythm & Blues" term was created to replace the designation "race music," which until then was the stardard catch-all phrase used in reference to most music made by blacks at the time. After the "race music" term was deemed offensive, Billboard began using the Rhythm & Blues moniker Wexler created. The meaning behind the name? The "rhythm" part comes from the music's typical dependance upon four-beat measures or bars and employ a backbeat (beats two and four accented in each measure).
Evolution of the Phrase:
The "blues" portion of the name came from the lyrics and melodies of the songs, which were often sad, or 'blue' during the music's emergence in the World War II era. Over time the name was shortened to R&B as a matter of convenience. By the 1970s, rhythm and blues was also being used as a blanket term to describe soul and funk as well. And today, the term can be used to loosely define most sung African-American urban music, even though soul and funk can be placed in categories of thier own.