Primary memory is the internal working memory of a computer, and it includes RAM and the cache. Secondary storage is also called external memory, and it includes the computer’s hard drive.
Primary storage is the fastest memory in the computer, but it only holds information for a short period of time while the computer is running. The data from primary storage tends to go away after the computer is turned off. When a user activates a program on a computer, data is moved from secondary storage devices into the RAM and cache of primary storage in order for the computer to actually use it. Secondary storage includes a CD-RW, a USB thumb drive, a tape drive, a floppy disk or anything else that is not used for the computer’s main memory. Anything stored in primary memory that needs to be remembered in the long run is transferred back to secondary memory when it is saved. Basically, it goes from the computer’s RAM and other places to the hard drive. The computer needs to access the information quickly to run it right away, which is the purpose of primary storage and the reason it is the fastest moving of the two storage types.