-stores information permanently  -in order to transfer info, mm and secondary storage must be directly connected -ex: hard disks, flash drives, and cd-roms
secondary storage (sometimes called backing storage) is the name for all of the devices (apart from rom and ram) that can store data in a computer system
this is the slowest and cheapest form of memory. it cannot be processed directly by the cpu. it must first be copied into primary storage (also known as ram).