this is sometimes called auxiliary storage, it cannot be read directly by the cpu. non-volatile. large capacities, can sometimes be removable. examples are hard disk, usb flash drive, ssd, cd-r.
nonvolatile. examples include local storage (hard drive), removable storage (flash drive), cloud storage. slower than ram. for storage between computer power cycles.
an architectural entity that encapsulates a subset of the system's functionality and restricts access to that subset