The lesson discusses the origins and evolution of rock music, specifically rock and roll, which became the dominant form of popular music in the developed world during the second half of the 20th century. It highlights the genre’s roots in African-American blues and its emergence alongside technological advancements and post-World War II prosperity, allowing for greater access to music. Key figures such as Elvis Presley and Chuck Berry shaped the genre, with their innovative styles and cultural impact defining rock and roll during the 1950s. The lesson emphasizes how rock music not only represented youth culture but also grew and evolved as its audience, the baby boomers, matured.