Rock and roll (often written as rock & roll, rock 'n' roll, or rock 'n roll) is a genre of popular music that evolved in the United States during the late 1940s and early 1950s. It originated from black American music such as gospel, jump blues, jazz, boogie woogie, rhythm and blues, as well as country music. While rock and roll's formative elements can be heard in blues records from the 1920s and in country records of the 1930s,[4] the genre did not acquire its name until 1954.

According to journalist Greg Kot, 'rock and roll' refers to a style of popular music originating in the United States in the 1950s. By the mid-1960s, rock and roll had developed into 'the more encompassing international style known as rock music, though the latter also continued to be known in many circles as rock and roll.'For the purpose of differentiation, this article deals with the first definition. In the earliest rock and roll styles, either the piano or saxophone was typically the lead instrument. These instruments were generally replaced or supplemented by guitar in the middle to late 1950s. The beat is essentially a dance rhythm with an accentuated backbeat, almost always provided by a snare drum. Classic rock and roll is usually played with one or two electric guitars (one lead, one rhythm) and a double bass (string bass). After the mid-1950s, electric bass guitars and drum kits became popular in classic rock.

In discussing Alan Freed's contribution to the genre, two significant sources emphasized the importance of African-American rhythm and blues. Greg Harris, then the Executive Director of the Rock n Roll Hall of Fame, offered this comment to CNN 'Freed’s role in breaking down racial barriers in U.S. pop culture in the 1950s, by leading white and black kids to listen to the same music, put the radio personality 'at the vanguard' and made him 'a really important figure''. After Freed was honored with a star on the Hollywood Walk of Fame, the organization's Web site offered this comment 'He became internationally known for promoting African-American rhythm and blues music on the radio in the United States and Europe under the name of rock and roll'.