CD-ROM stands for Compact Disc Read-Only Memory. A CD-ROM, also referred to as a compact disc, is read by a computer with an optical drive.
The ROM in CD-ROM indicates that the CD is read-only, which means it cannot be erased or written over. The CD-ROM is used as a storage medium with a capacity of 700MB. CD-ROM discs are formatted in such a way that they can store any file type. As of 2014, CD-ROMs are popular as distribution vehicles for video games and software. The discs are made of polycarbonate plastic and a layer of aluminum. They are 1.2 mm in thickness and 120 mm in diameter.