The document provides a timeline and overview of popular music from the 1950s through the 1990s. It summarizes each decade, highlighting some of the major musical artists and genres that were popular during that time period. For each decade it also lists 3 hit songs from that era, describing who performed each song and some background about its release and popularity. The document aims to concisely chronicle the evolution of popular music over the second half of the 20th century.