Rhythm and blues, frequently abbreviated as R&B or R'n'B, is a genre of popular music that originated within African American communities in the 1940s. The term was originally used by record companies to describe recordings marketed predominantly to African Americans, at a time when "rocking, jazz based music ... [with a] heavy, insistent beat" was starting to become more popular. In the commercial rhythm and blues music typical of the 1950s through the 1970s, the bands usually consisted of a piano, one or two guitars, bass, drums, one or more saxophones, and sometimes background vocalists. R&B lyrical themes often encapsulate the African-American history and experience of pain and the quest for freedom and joy, as well as triumphs and failures in terms of societal racism, oppression, relationships, economics, and aspirations.

The term "rhythm and blues" has undergone a number of shifts in meaning. In the early 1950s, it was frequently applied to blues records. Starting in the mid-1950s, after this style of music had contributed to the development of rock and roll, the term "R&B" became used in a wider context. It referred to music styles that developed from and incorporated electric blues, as well as gospel and soul music. By the 1970s, the term "rhythm and blues" had changed once again and was used as a blanket term for soul and funk.

In the late 1980s, a newer style of R&B developed, becoming known as "contemporary R&B". This contemporary form combines rhythm and blues with various elements of pop, soul, funk, disco, hip hop, and electronic music.

Although Jerry Wexler of Billboard magazine is credited with coining the term "rhythm and blues" as a musical term in the United States in 1948, the term had been used in Billboard as early as 1943. However, the company's first list of songs popular among African Americans was named Harlem Hit Parade; created in 1942, it listed the "most popular records in Harlem," and is the predecessor to the Billboard RnB chart. "Rhythm and Blues" replaced the common term "race music", a term coined by Okeh producer Ralph Peer based on the common self description by the African American press as "people of race." The term "rhythm and blues" was then used by Billboard in its chart listings from June 1949 until August 1969, when its "Hot Rhythm & Blues Singles" chart was renamed as "Best Selling Soul Singles". Before the "Rhythm and Blues" name was instated, various record companies had already begun replacing the term "race music" with the term "sepia series". "Rhythm and blues" is often abbreviated as "R&B" or "R'n'B".

In the early 1950s, the term "rhythm & blues" was frequently applied to blues records. Writer and producer Robert Palmer defined rhythm & blues as "a catchall term referring to any music that was made by and for black Americans". He has also used the term "R&B" as a synonym for jump blues. However, AllMusic separates it from jump blues because of R&B's stronger gospel influences. 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. Well into the 21st century, the term R&B continues in use (in some contexts) to categorize music made by black musicians, as distinct from styles of music made by other musicians.

In the commercial rhythm and blues music typical of the 1950s through the 1970s, the bands usually consisted of piano, one or two guitars, bass, drums, and saxophone. Arrangements were rehearsed to the point of effortlessness and were sometimes accompanied by background vocalists. Simple repetitive parts mesh, creating momentum and rhythmic interplay producing mellow, lilting, and often hypnotic textures while calling attention to no individual sound. While singers are emotionally engaged with the lyrics, often intensely so, they remain cool, relaxed, and in control. The bands dressed in suits, and even uniforms, a practice associated with the modern popular music that rhythm and blues performers aspired to dominate. Lyrics often seemed fatalistic, and the music typically followed predictable patterns of chords and structure. R&B lyrical themes often encapsulate the African-American experience of pain and the quest for freedom and joy, as well as triumphs and failures in terms of relationships, economics, and aspirations.^{[citation needed]}

One publication of the Smithsonian Institution provided this summary of the origins of the genre in 2016.

"A distinctly African-American music drawing from the deep tributaries of African American expressive culture, it is an amalgam of jump blues, big band swing, gospel, boogie, and blues that was initially developed during a thirty-year period that bridges the era of legally sanctioned racial segregation, international conflicts, and the struggle for civil rights".