Compact disc (CD) is a digital optical disc data storage format that was co-developed by Philips and Sony in 1982. CDs are commonly used to store digital audio and have a capacity of 700 MB of data or 80 minutes of audio.
CDs are made from a polycarbonate plastic disc which is coated with an aluminium reflective layer. Digital data is encoded onto the disc in the form of a spiral track of pits, each functionally equivalent to a binary digit. The data is read from the CD by focusing a laser beam onto the disc surface and measuring the reflected beam.
CDs typically come in two formats: CD-DA (Compact Disc Digital Audio) and CD-ROM (Compact Disc Read-Only Memory). CD-DA is used for audio data storage, while CD-ROM is used for software and other data. Cable can also be used to write data to CD-Rs (CD Recordables), which are recordable CDs that users can write data to.
CDs are popular in many applications due to their larger storage capacity compared to other digital formats. They are widely used for music storage, computer software, and games. CDs offer higher sound quality than other audio formats such as tapes and vinyl records, and are known for their durability and reliability.
