Computer storage medium is a term used to describe the various ways in which data can be stored on a computer. The most common forms of computer storage medium are discs, CD-ROMs, and memory chips. Discs are circular pieces of plastic with data stored on them in the form of tiny pits. CD-ROMs are similar to discs but are made of polycarbonate and have data stored on them in the form of microscopic bumps. Memory chips are small integrated circuits that store data in the form of electrical charges.