What is a ring on a computer disk where data can be written?

Answer 1

Ring refers a physical are of the hard disk plate.

On a hard disk, data is stored in thin, concentric bands. A drive head, while in one position can read or write a circular ring, or band called a track.

Please refer to this link for details (source):
http://www.ntfs.com/hard-disk-basics.htm#Making%20Tracks

regards,
Philip T

Answer 2

i think what u mean is tracks ..

the break up is as follows ..

hard disk - platters or surface - tracks - sectors -bytes - bits