What is a Compact Disk (CD) - A compact disc (or CD) is an optical disc used to store digital data, originally developed for storing digital audio. It is the standard playback format for commercial audio recordings today. A standard compact disc, often known as an "audio CD" to differentiate it from later variants, stores audio data in a format compliant with the red book standard. An audio CD consists of several stereo tracks stored using 16-bit PCM coding at a sampling rate of 44.1 kHz. Standard compact discs have a diameter of 120 mm, though 80 mm versions exist in circular and "business-card" forms.
The design of the CD was originally conceived as an evolution of the gramophone record, rather than primarily as a data storage medium. Only later did the concept of an 'audio file' arise, and the generalising of this to any data file. As a result, the original CD format has a number of limitations; no built-in track names or disc naming for example. Online services such as CDDB were developed to work around these shortcomings in the computer age.
What is a record: A gramophone record or phonograph record (often simply record) is an analogue sound recording medium: a flat disc rotating at a constant angular velocity, with inscribed spiral grooves in which a stylus or needle rides. Analogue audio recording onto a disc was the main technology used for the storing of recorded sound for most of the 20th century.