It is also known as the non-volatile memory or external memory. It is used to store the information permanently, but it works slower than the primary memory. This memory is accessed through input and output routines in the system, unlike the primary memory that can be accessed directly. The data of the secondary memory is transferred to the primary memory and then is accessed by the CPU. Moreover, the storage in secondary memory is low because of the low cost per bit. The operating speed of this memory is low as compared to primary memory. Some of the secondary memory are Magnetic Disk, Floppy Disk, Hard Disk and Optical Disks.
It is used for input and output operations at fast access speed. It is used to provide a way to fetch instructions to CPU at the speed of CPU because input and output operations access slowly in the main memory. The CPU searches the cache memory before searching for the main memory. Also, it is located close to CPU that renders it access faster than the other memory.