What is the difference between primary storage secondry storage and off line storage

"Primary storage" is the fastest memory in the computer, but only holds information for a short period of time while the computer is running. "Secondary storage" includes a CD-RW, a USB thumb drive, a tape drive, a floppy disc or anything else that is not used for the computer's main memory. A term used to describe any storage medium that is non-volatile and whose data cannot be accessed by the computer once removed. A good example of off-line storage is a USB thumb drive. 
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B: people should evaluate different forms of savings vehicles based on their needs