Homonym: cd (Certificate)
A "cd" refers to a compact disc, a digital optical disc storage format used to store data, including music, software, and other digital files. Introduced in the early 1980s, CDs became popular for their ability to hold up to 700 megabytes of data and provide high-quality audio playback. They are read by laser technology in CD players and computers.
In addition to music, CDs can also be used for data storage and software distribution. The format has largely been replaced by digital downloads and streaming services, but CDs remain a physical medium for collectors and audiophiles who appreciate their sound quality.