The document compares CDs and the iPod, discussing their histories and advantages/disadvantages. CD production began in the 1980s but didn't become popular until the 1990s, while iPods were first launched in 2001 and have since sold over 220 million units. Some advantages of CDs are that they play in cars and are compact, while disadvantages include being scratch-prone and only holding 20 tracks; iPods can hold thousands of songs, are portable, and allow private listening, but require a computer and charging and don't play in cars without extras. iPod usage has greatly increased since the early 2000s while CD purchases have declined.