A computer's optical drive is a disc drive that reads optical media like CDs, DVDs, and Blu-rays using a laser. Both internal and exterior optical disks, which are housed in distinct cases and installed inside computers and linked to the processor directly, are options. Most optical devices can write to readable and rewritable discs in addition to reading optical discs.

"Optical" is defined as "pertaining to perception or light." It alludes, in the context of optical drives and optical media, to the laser that scans the bottom of a rotating plastic disc, picking up a sequence of ridges and holes that house stored digital data. A low-power laser that scans data, a medium-power laser that erases rewritable discs, and a high-power laser that writes data to a disc are all included in optical devices that can write to discs.

The pits and ridges on each new iteration of optical media are smaller and are scanned by shorter lasers; for example, a CD has pits that are 800 nm long, while a Blu-ray disc has pits that are only 150 nm long. A Blu-ray optical drive, for instance, can rotate a disc at more than 9,000 rotations per minute while reading data. The pace at which an optical drive can detect the holes on a disc relies on how quickly the disc is rotating. Optical drives are slower than hard drives and solid-state drives even when a disc is moving that quickly. However, hard media—particularly high-definition videos and platform video games—is most frequently used to share large quantities of data due to its low cost and portability.