Final answer:
Alan Freed coined the term rock and roll and popularized the genre as a disc jockey, bringing it to a wide American audience and encouraging a cultural shift in music.
Step-by-step explanation:
Alan Freed is credited with coining the term rock and roll for the new style of music that revolutionized the popular music world in the mid-20th century. Artists like Bill Haley, with his hit song "Rock Around the Clock," and Elvis Presley, who merged country music and rhythm and blues, pushed this genre into the mainstream.
This new musical movement grew from African American rhythm and blues roots and was characterized by its heavy rhythm, simple lyrics, and was an amalgamation of gospel, blues, country, jazz, and R&B influences.
The disc jockey who popularized rock and roll was Alan Freed. Freed played a pivotal role in naming and promoting this genre, especially by playing it on the radio in Cleveland and organizing the first rock and roll concert.
Freed's influence helped to elevate rock and roll's status and bring it to a broader American audience, encouraging a feeling of youthful rebellion and beginning to break down racial barriers in music.