In computer terminology, what does "ROM" stand for?

In computer terminology, ROM stands for read-only memory.

Read-only memory is a type of non-volatile memory, meaning it retains stored data even when a device is switched off. Traditionally, ROM contained instructions permanently embedded during manufacturing. Those instructions could include firmware: low-level software that helps hardware start up and perform essential functions.

The name is slightly less absolute in modern computing. Technologies such as PROM, EPROM, EEPROM and flash memory can be programmed or reprogrammed under particular conditions, yet they remain part of the broader ROM family because they are used to preserve data without continuous power. Modern devices often store firmware in flash rather than in strictly unchangeable mask ROM.

ROM is commonly confused with RAM, or random-access memory. RAM is volatile working memory used for active programs and data; its contents normally disappear when power is removed. ROM is intended for persistent instructions or data. In everyday technology discussions, “ROM” can also mean a firmware image, such as a custom ROM for an Android device, even when the underlying storage is technically writable flash memory.