A track is logical sub-division of the media.
Data items on a CD are not stored in concentric circles. They are rather arranged in an extended spiral-shaped line whose origin is at the center of the CD. The line runs from the in-side to the outside. Those sections on the spiral on which data items are located are called tracks. Up to 99 tracks may be stored on an Audio-CD. One track generally corresponds to one piece of music on the CD.