CDsDVDsBluray
CDs, DVDs, and Blu-ray discs are optical storage media used to store digital data, video, and audio. They encode data as microscopic pits and lands on a polycarbonate substrate, read by a laser in a player or drive. Each format uses a different laser wavelength and storage density, which affects capacity and compatibility. CDs originated in the 1980s for consumer audio and later supported data storage; DVDs emerged in the 1990s to provide higher capacity for movies and software. Blu-ray, introduced in the mid-2000s, further increased density to support high-definition video and large data sets.
Capacities and common variants. A standard CD holds about 700 MB of data or 74–80 minutes of
Uses and distribution. CDs are widely used for music and software distribution; DVDs for movies, television,
Durability and current status. Optical discs are susceptible to scratches, surface damage, and environmental factors, and