Optical disc
Alternatively referred to as optical media and optical storage, an optical disc drive (ODD) or optical disk is any storage media that holds content in digital format and is read using a laser assembly is considered optical media. The most common types of optical media are Blu-ray, CDs, and DVDs. Computers can read and write to CDs and DVDs using a CD Writer or DVD Writer drive, and a Blu-ray is read with a Blu-ray drive. Drives such as a CD-R and DVD-R drive that can read and write information to discs are known as magneto-optic (MO).
There are three main types of optical media: CD, DVD, and Blu-ray disc. CDs can store up to 700 megabytes (MB) of data and DVDs can store up to 8.4 GB of data. Blu-ray discs, which are the newest type of optical media, can store up to 50 GB of data. This storage capacity is a clear advantage over the floppy disk storage media (a magnetic media), which only has a capacity of 1.44 MB. Another advantage that optical media have over the floppy disk is that it can last up to 7 times longer, due to its improved durability.
Note: A CD drive can only read CD discs, a DVD drive can only read DVD and CD discs, and Blu-ray can read CD, DVD, and Blu-ray discs.
Tip: Because these discs are read by light (optical) they should be referred to as an optical disc, not optical disk.
Also see: CD definitions, Magnetic media, Magneto-optic