Typically a disk drive consists of a disk pack consisting of several platters stacked like phonograph records.
Informations is recorded magnetically usually on both sides.
All the platters move as one unit. Each platter is divided into concentric rings called tracks , and each track is divided into sectors . Data transferred to and from a sector is called a block . The number of sectors per track and number of bytes per block is determined by how the disk is formatted . Some disk units allow the formatting to be done under software control.