The full form of ROM is Read Only Memory. ROM is a type of computer memory that stores data that can only be read, not written. It is a non-volatile type of memory, which means that data stored in it is retained even if power is lost. ROM is useful for storing software or data that is rarely changed throughout the life of the system, also known as firmware. There are different types of ROM, including MROM (Mask Read Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable Programmable Read-Only Memory), and EEPROM (Electrically Erasable Programmable Read-Only Memory) . MROM is a memory chip that is made with its data, while PROM is a blank chip that can be programmed by the user. EPROM is an exception because the data bound could be deleted if the EPROM chip is shown to extreme ultraviolet light for some time. EEPROM is similar to EPROM, but the data can be erased electrically.