Rhythm & Blues developed during the Great Depression years as a somewhat underground sound, although many R&B songs began crossing over into the pop charts during this era. The difference between blues and R&B was that blues closely followed specific musical scales and riffs that centered around "blue notes" in minor keys, while R&B broke away from blues patterns and focused on emotional expression of the performer. Some of the first major African-American musical stars were Mamie Smith, Bessie Smith and Louis Armstrong.
Many architects of 1950s rock and roll credit R&B artists merging their style with country music to create an exciting new presentation, enhanced by electric sound. Some early rock and roll hits, such as "Hound Dog" by Elvis Presley, were covers of R&B songs, which actually brought more attention to R&B as a genre in the 1950s. Chuck Berry, Little Richard and Fats Domino were early leaders of the style that bridged R&B with early rock. By the end of the decade, doo-wop artists such as The Platters and a carefree-spirited sound by Ray Charles helped shape early soul music.
The first big artist for Motown Records in the early sixties was Smokey Robinson & The Miracles. Starting with the hit "Shop Around" in 1960, they began to craft a smooth, infectious sound that became the hallmark of the Motown sound. Other landmark soul hits that followed were "My Guy" by Mary Wells and the more raw "Fingertips" by Stevie Wonder. By the mid-sixties, the pop charts were full of Motown hits by The Supremes, Martha & The Vandellas, The Four Tops, The Temptations and Marvin Gaye. Many Motown hits were written by the songwriting team of Holland-Dosier-Holland. At the same time, a more blues-based aggressive presentation came from James Brown, Jackie Wilson and Aretha Franklin. Many historians credit James Brown as the artist who popularized funk music, a harder version of soul. The end of the sixties marked the beginning of The Jackson 5, a group of youngsters who would attract a whole new generation of kids of all cultures to celebrate what was by then known as soul music.
Since blasting onto the music scene in the sixties, the term "soul" has been applied to many sub-genres of R&B and sometimes as a synonym for R&B. The TV dance show Soul Train began syndication in 1971. Barry White introduced an even more polished orchestral and beat-oriented sound to soul in the seventies and he is credited as the first major disco artist. By the late-eighties, "R&B" was the more widely used blanket term for what was and still is called soul.