CDsDVDs

CDs and DVDs are optical disc formats used for storing digital data, including audio, video, software, and other files. The term CDsDVDs covers the common consumer media types that share a similar construction: a polycarbonate plastic substrate, a reflective metal layer, and a protective coating, read by a laser in optical drives. Their diameters are 120 millimeters for the standard disc and 80 millimeters for mini discs, used mainly for data or music.

CDs originated in the early 1980s as a format for music, developed by Philips and Sony. This led to data-oriented variants such as CD-ROM, CD-R, and CD-RW, which added data storage capability and erasable recording. The DVD format emerged in the mid to late 1990s, providing higher capacity by using tighter track pitch and two-layer designs: common DVD-ROM, DVD-Video, DVD-R, DVD+R, DVD-RW, and DVD+RW, with typical capacities of 4.7 GB per layer and up to 8.5 GB on dual-layer discs. A variety of encoding and error-correction systems, such as CIRC for CDs and ECC for DVDs, protect data integrity.

Capacity and longevity: standard CDs hold about 700 MB or 80 minutes of audio, while standard single-layer DVDs hold about 4.7 GB. Rewritable variants allow multiple recording cycles, though performance can be affected by scratches, exposure, and handling. The discs use red laser light (CD around 780 nm; DVD around 650–635 nm) for reading data, enabling compatibility with a wide range of drives.

Uses and current status: CDs are still used for music and data distribution, while DVDs remain common for video playback and software distribution. In recent years, optical media have declined in consumer prominence due to streaming and flash storage, though they remain in use for archival or offline storage in some contexts.