CDs are one of the most popular ways of storing music and computer data. A CD is a thin, circular disc of metal and plastic which uses flashing laser lights to record and read back information.
CDs were originally used just for storing music. Later, they were used for storing videos as well. Each disc could store 74 minutes of stereo sound. The technology behind CDs was invented in the late 1960s by James T. Russell.
An avid music fan, he longed for a sound-recording system that would reproduce music more exactly than LP records . and cassette tapes.
The difference between CDs and DVDs is the amount of information they can store. A CD can hold 650 megabytes, or million characters of data, whereas a DVD can cram in at least seven times more data. In effect, a DVD can do anything that CD does, and more efficiently.