The compact disc or CD is turning 40 years old in the U.S. this year. The first commercial CD was released in Japan in October of 1982, but they didn't make their way to the United States until March 1983. The CD served as an alternative to larger vinyl records and bulkier cassette tapes. When the first CD came out, it could hold up to 74 minutes of music, and it was only 4.5 inches in diameter. It would eventually overtake cassette sales by the late 1980s.