An optical disk is a type of computer disk that uses optical storage techniques and technology to read and write data. It is a flat, usually disc-shaped object that stores information in the form of physical variations on its surface that can be read with the aid of a beam of light. Optical disks rely on a red or blue laser to record and read data. Most of todays optical disks are flat, circular, and 12 centimeters in diameter. They can store analog information, digital information, or both on the same disc. Optical disks are used for the distribution of media and data, and long-term archival.

An optical disk drive (ODD) is a part of computer hardware that is used for CDs/DVDs/BDs reading and writing. It uses a laser beam to read the data from the disk as it is spinning. Optical disk drives can be found in regular PCs and laptops, although they have become less common in recent years. Optical disk drives are an integral part of standalone appliances such as CD players, DVD players, Blu-ray Disc players, DVD recorders, and video game consoles.

In summary, an optical disk is a type of computer disk that uses optical storage techniques and technology to read and write data. An optical disk drive is a part of computer hardware that is used for CDs/DVDs/BDs reading and writing.