An excellent reference is a publication of the National Bureau of Standards, NBS Special Publication 500-101, Care and Handling of Computer Magnetic Storage Media. An optical disk resembles a phonograph record and may be from 3.25 to 14 inches in diameter. The information is represented on the disk by a change in the surface reflectivity and is read by using a low-powered laser to sense the reflectivity changes. Optical disks are not highly sensitive to environmental factors. Unlike floppy disks and magnetic tapes, optical disks are not damaged by normal heat and humidity fluctuations and are not affected by magnetic force fields.
Optical disks are generally durable and withstand all but the most abusive handling.