A digital optical disc for storing audio, video, or data. First released in Japan in October 1982, the CD was the second optical disc format to reach the market, following the larger LaserDisc (LD). It employs the Compact Disc Digital Audio (CD-DA) standard and is capable of holding uncompressed stereo audio. By 2007, over 200 billion CDs (including audio CDs, CD-ROMs, and CD-Rs) had been sold worldwide. Standard CDs have a diameter of 120 mm (4.7 in) and typically hold up to 74 minutes of audio or approximately 650 MiB (681,574,400 bytes) of data. This was later regularly extended to 80 minutes or 700 MiB (734,003,200 bytes) by reducing the spacing between pits.
Physical Characteristics
CDs are made of polycarbonate plastic, with a diameter of 120mm (4.7 inches) and a thickness of 1.2mm. Data is encoded on the disc as a series of microscopic pits and lands read by a laser in the CD player.
Data Storage
The standard CD format can hold up to 74-80 minutes of uncompressed audio or 650-700MB of data. Audio CDs are used for music distribution, while data CDs can store various types of digital information, including software, video, and documents.
Advantages and Disadvantages
- Durability: CDs are known for their durability and resistance to scratches and dust.
- Portability: They are portable and easy to carry, making them a convenient storage medium.
- Audio Quality: CDs offer good audio quality, which was a significant improvement over previous analog formats.
- Replacement: CDs have largely been replaced by newer technologies like digital downloads, streaming, and USB drives for data storage.
Additional Acronyms for CD
- CD - Continuous Delivery or Continuous Deployment
