What is "cylinder-head-sector"

n. (context computing English) An addressing system of hard drives where the hard drive is addressed by its cylinders, heads, and sectors.

Cylinder-head-sector, also known as CHS, is an early method for giving addresses to each physical block of data on a hard disk drive. In the case of floppy drives, for which the same exact diskette medium can be truly low-level formatted to different capacities, this is still true.

Though CHS values no longer have a direct physical relationship to the data stored on modern storage media except for floppy disks, virtual CHS values (which can be translated by disk electronics or software) are still being used by many utility programs and file systems.