Secondary Memory :

There is another kind of storage device, apart from primary or main memory, which is known as secondary memory. Secondary memories are non volatile memory and it is used for permanent storage of data and program.

Example of secondary memories:

Hard Disk,  Floppy Disk,  Magenetic Tape	------	These are magnetic devices,
CD-ROM	------	is optical device
Thumb drive (or pen drive)	------	is semiconductor memory.