disksCDs

Disks and CDs are two broad classes of data storage media used in computers and consumer electronics. Disks typically refer to magnetic disk storage, including hard disk drives (HDDs) and solid-state drives (SSDs), which provide non-volatile storage for operating systems, software, and data. CDs, or compact discs, are optical discs designed to store digital data and audio, read by a laser. The term disksCDs is not a standard label; this article treats disks (magnetic storage) and CDs (optical storage) as distinct, yet complementary, media in computing.

Magnetic disks, or hard disks, use rotating platters coated with magnetic material. Data are written and read by heads on actuator arms as the platters spin, typically at speeds such as 5400 or 7200 revolutions per minute in consumer drives, with higher speeds in performance models. SSDs store data in flash memory without moving parts, offering faster access times and greater durability. Disks differ in capacity, reliability, latency, and throughput; interfaces include SATA and the faster NVMe over PCIe for SSDs. Modern systems increasingly rely on SSDs for primary storage, with HDDs used for larger, cheaper backups. Longevity and wear characteristics vary by technology and workload.

Compact discs are plastic substrates with data encoded in pits and lands. Formats include CD-ROM for data, Audio CD for music, and writable variants such as CD-R and CD-RW. Typical single-layer CD capacities are around 650–700 MB. Optical discs have a long archival potential under proper conditions, but are susceptible to scratches, exposure, and degradation over time. CDs remain common for distribution, media playback, and some archival applications, though cloud storage and hard drives have largely supplanted them for routine data storage.