Final answer:
CD-ROMs and DVDs are examples of optical discs, which utilize laser technology to store and retrieve digital information in the form of pits on the surface of the disc, unlike magnetic tapes and disks that use magnetic fields for data encoding.
Step-by-step explanation:
In the context of storage devices, CD-ROMs and DVDs are examples of optical discs. These storage media use lasers to read and write data. Information on CDs and DVDs is encoded in the form of tiny pits and lands on the disc's surface, which a laser beam can read as it reflects off these indentations. This digital information is interpreted as a series of 0s and 1s, which represent the binary data stored on the disc.
Magnetic tapes and magnetic disks, on the other hand, store information using magnetic fields to encode data on a medium. For example, computer hard drives encode data on spinning disks coated with a magnetic material, while magnetic tapes, like those used in cassettes, record information on long strips of magnetic tape.
Main memory devices, such as RAM, are different altogether, providing temporary storage that a computer's processor can access quickly when performing tasks. Optical discs, however, are permanent storage solutions that can hold large amounts of data in a non-volatile format.