A compact disc (CD) is a digital optical disc that was developed to store and play back audio recordings. It is a round, flat disc made of polycarbonate plastic, typically measuring 12 centimeters (4.7 inches) in diameter. CDs revolutionized the music industry by providing a more durable and portable medium for storing and playing music than vinyl records or cassette tapes. CDs can store various types of data besides audio. In addition to audio CDs, there are compact disk read-only memory (CD-ROMs) that store data such as software, video games, and multimedia content. Compact disk recordable (CD-Rs) and compact disk rewritable (CD-RWs) allow users to burn their own data, including music, videos, photos, and documents onto the discs.

The first compact disc was manufactured in August 1982 and was released in October 1982 in Japan. CDs are fragile and prone to scratches, which can affect disc readability. CDs have declined in popularity due to the rise of digital music and streaming services, but they are still used by certain groups of people. Audiophiles, for example, often prefer the superior sound quality of CDs over compressed digital audio files. CDs are also favored by collectors, as they provide a tangible medium with cover art and liner notes. Additionally, CDs are sometimes used in environments where internet access is limited or unavailable, such as in cars or remote locations.

To ensure the longevity of CDs, it is important to handle and store them properly. Avoid touching the shiny surface of the CD (the side with the data) to prevent fingerprints and scratches. Hold the CD by its edges or use the center hole. When storing CDs, keep them in their protective jewel cases or sleeves.