1. 1977 Movie Saturday Night Fever popularizes "disco" music

2. 1987 Sony introduces the Walkman Hip hop, a blend of rock, jazz, soul with African drumming, born in the South Bronx

3. 1979 Sugarhill Gang releases "Rapper's Delight", popularizes rap, combines elements of disco and rock with urban street music

4. 1981 MTV, music television, debuts with nonstop music videos, presentation becomes as important as the sound

5. 1982 Michael Jackson releases album "Thriller", ties with Eagles' "Their Greatest Hits," as best selling album in history; "Thriller" music video becomes a classic

6. 1983 Compact discs begin to replace vinyl records

7. 1984 Madonna’s “Like A Virgin Makes” her a major star

8. 1990 Grunge rock, a combination of various rock styles, rises in Seattle; features such bands as Nirvana, Pearl Jam, Metallica

9. 1995 Rock and Roll Hall of Fame and Museum opens in Cleveland

10. 2000 The Internet transforms music scene as companies offer free music over the Internet without paying copyright fees. Music industry executives take the issue to court. A ruling prompts Napster to stop distributing copyrighted music free and team up with industry giant Bertelsmann to provide material for a fee.

11. 2001 In 2000, digital music players were either big and clunky or small and useless with equally terrible user interfaces. Apple saw the opportunity and announced the release of the iPod, their first portable music player on October 23, 2001.

12. 2003 Apple Computer introduces Apple iTunes Music Store, which allows people to download most songs for 99 cents each.