Which type of memory is considered non-volatile?

Non-volatile memory refers to a type of storage that retains data even when the power is turned off. ROM, or Read-Only Memory, is specifically designed to be non-volatile, meaning it holds its contents indefinitely without a continuous power supply. This type of memory is essential for storing firmware or software that is not intended to be modified frequently, such as the computer's BIOS.

In contrast, RAM (Random Access Memory) and cache memory are examples of volatile memory, which means they require power to maintain the stored information. Once power is lost, any data held in RAM or cache is lost. Virtual memory, while it may involve complex storage techniques like paging to maximize RAM capacity, also relies on the volatile nature of physical memory. Thus, ROM stands out as the correct answer for non-volatile memory types.