Compact Disk Read Only Memory (CD-ROM) is a storage medium commonly used for storing and retrieving digital data. It is part of the optical disc family and was primarily designed for the distribution of computer software, but its usage has extended to encompass multimedia content, reference materials, and other data types.
A CD-ROM is a non-volatile medium, meaning that the data stored on it remains intact even when the power supply is disconnected. It consists of a flat, circular disc made of polycarbonate plastic, with a diameter of 12 cm (or 8 cm in some cases). The disc has a metallic layer that reflects the laser beam used for data retrieval and a protective layer to prevent damage.
The data on a CD-ROM is stored as microscopic indentations, called pits, on the metallic layer. These pits are formed during the manufacturing process using a master disc, and they represent binary data in the form of 1s and 0s. When the disc is read by a CD-ROM drive, a laser beam scans the surface, detecting the presence or absence of pits and translating them into digital information.
CD-ROMs are labeled "read-only memory" as the data written to them during the manufacturing process cannot be altered or erased by the end-user. However, this read-only limitation was later overcome with the development of CD-R (CD-Recordable) and CD-RW (CD-ReWritable) technologies, which allow users to write data onto blank discs.
In summary, a CD-ROM is a flat, circular, optical storage medium capable of storing large amounts of digital data in a non-volatile manner. It is widely used for software distribution, multimedia content, and reference materials.
