Definition: ROM

ROM, which stands for Read-Only Memory, is a storage medium used in your computer to store data. The data stored in ROM can only be read and is near impossible to modify. Unlike RAM, ROM is non-volatile, meaning that even when you turn off your computer, the contents of ROM still remain.

Rom is the only non-volatile part of main memory.

ROM is mainly used for firmware, which consists of a few kilobytes of code that instruct the computer what to do when it powers on (hardware diagnostics, loading the operating system, graphic card firmware, etc.) An example of ROM is the cartridge used in video game​ consoles that allows the system to support multiple video games.

EEPROM (electrically erasable programmable read-only memory), a type of ROM, can be erased and reprogrammed only through the use of higher than normal voltage. A form of EEPROM is flash memory, which utilizes PC voltages to erase and reprogram.