What is the term for data that cannot be modified, or can only be modified slowly or with difficulty?

The term that describes data which cannot be modified, or can only be modified slowly or with difficulty, is read-only memory (ROM). This type of memory is designed to retain information even when the power is turned off and is often used for firmware or software that is not intended to be changed frequently.

ROM is inherently non-volatile, meaning that the data is preserved without a power supply, and it is primarily written during the manufacturing process. This makes it an ideal choice for storing system boot instructions, hardware configuration data, and other critical information that does not need constant updates. Unlike volatile memory types, such as dynamic memory, which can change frequently and requires power to maintain its contents, ROM provides a stable, unchangeable data storage solution, ensuring the integrity of the information stored within it.