The encoding of a CD is read from the centre towards the outside of the disc. Information is stored in the form of pits, separated by lands, organised along a spiral groove six kilometres long. A CD can contain up to 22,188 spirals totalling nearly three billion pits.

These pits are incredibly small with a width of 0.5 microns and a depth of 0.11 microns. Spirals are separated from each other by 1.6 microns. As a measure of comparison, the thickness of a hair equates to the total width of thirty spirals.