Depending on the media type, CDs, DVDs, UDOs (Ultra Density Optical), WORM (Write Once Read Many), Magneto-optical, optical discs consist of one side or two sides and one or several data layers on each side. However most optical disks are made of four key layers:

• - Substrate Layer
• - Data-Recording Layer
• - Metal Layer
• - Lacquer Layer

First comes a polycarbonate plastic substrate containing a shallow spiral groove extending from the inside to the outside diameter of the disk. On top of this substrate is an organic data-recording layer (cyanine, phthalocyanine or azo) followed by a thin metal reflective layer (aluminium, silver alloy, silver, silicon or gold) and finally an outer protective lacquer coating. Some disks are also topped with additional layers that improve scratch resistance, increase handling durability or provide surfaces suitable for labelling by inkjet or thermal transfer printers.

Unlike the other type of media, standards about optical disc lifetime exist or are being written. For instance the ISO 18921:2002, Imaging materials — Compact discs (CDROM); and the ISO 18927:2002, Imaging materials — Recordable compact disc systems, define the methods for estimating the life expectancy based on the effects of temperature and relative humidity. The ANSI/NAPM IT9.26 is preparing a draft on the life expectancy of magneto-optical (MO) discs.