Storage elements like hard disks and solid state drives are referred to as secondary memory. It may also be used to describe portable storage devices like Discs, DVDs, and USB thumb disks.

Secondary memory is not immediately read by the Processor like main memory is. Instead, information is first put into RAM before being sent to the CPU when it is retrieved from auxiliary memory. Since RAM offers much quicker data entry rates than auxiliary memory, it serves as a crucial intermediary. Computers can handle data much more rapidly by putting software applications and files into main memory.

Secondary memory usually has a much higher storing capability despite being much slower than main memory. A machine might, for instance, have a 1 TB hard disk but only 16 GB of Memory. Therefore, the auxiliary memory is approximately 64 times larger than the main memory on the machine. Secondary memory is also non-volatile, which means it can function even when its power source is off. However, when a computer is turned off or rebooted, Memory is deleted. As a result, "solid data" like the operating system, programs, and personal folders are kept in secondary memory.

"Secondary storage" is another name for auxiliary memory. Since internal storage devices are also sometimes referred to as "main storage devices," this word is somewhat unclear.