Computer users usually don't need to worry about using ROM: It's an essential part of the internal hardware of a computer and peripherals that tends to stay out of sight.

Think of ROM as you would the tires on an automobile. You don't usually need to worry about them, but they're used all the time.

ROM chips are accessed by the CPU and other processors in the system whenever they need specific instructions to accomplish a task -- for example, the startup sequence when you turn on your computer.

If the right type of ROM chip isn't there, the computer will be unable to perform that task.

Some types of ROM -- like EEPROM or Flash ROM -- allow a user to upgrade the basic input/output system (BIOS) on a ROM chip.

For example, a 28.8-kbps modem built two years ago might have the capacity to operate at 33.6 kbps, but is being held back by the BIOS. If such a modem has Flash ROM, you might be able to upgrade it by running a program (often called a "patch") to install the new version of the BIOS onto the component's ROM chip.