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Optical media are physical storage devices, like CDs, DVDs, and Blu-ray discs, that use a laser to read and write data. Digital data is encoded by burning microscopic pits and lands into the disc's reflective layer, and a laser reads these patterns to retrieve the information. This type of media is often used for long-term archiving, backups, and distributing software, music, and movies.

How it works

Reading: As the disc spins, a laser beam scans the data layer. The laser reflects differently off the "lands" (flat areas) and "pits" (indented areas), which is interpreted as binary data.

Writing: For recordable or rewritable discs, the laser changes the physical properties of the data layer to create the pits and lands that store the data.

Key characteristics

Durability: They are not affected by magnetic fields and can have a long lifespan.

Capacity: Modern optical media like Blu-ray offer significantly higher storage capacities compared to older media like floppy disks.

Versatility: They can be read-only (factory-pressed), write-once (CD-R, DVD-R), or rewritable (CD-RW, DVD-RW).

Current status: While their use has declined in favor of cloud storage and USB drives, they are still a cheap and reliable option for certain applications.