Editing Reading (computer) (section)

=== Optical discs ===
{{main article|Optical disc}}
Optical discs refer to the [[non-volatile]] flat, circular, usually polycarbonate discs. Data is stored in pits or bumps arranged sequentially on the continuous, spiral track extending from the innermost track to the outermost track, covering the entire disc surface. Data is read by a means of a laser; when the laser enters a pit, the focus of the laser is changed and interpenetrated by the reader's software.