The document discusses the history and genres of rock music. It notes that rock emerged in the mainstream in the 1960s with bands like The Beatles and The Rolling Stones. Rock has many subgenres like punk, blues, and garage rock. Instruments commonly used in early rock music included electric guitars, keyboards, bass guitar and drums. Today, successful rock groups typically consist of a guitarist, singer, bassist and drummer. Music videos often show bands playing live or at house parties.