Question: Any storage device added to computer beyond the immediately usable main storage is known as:

Answer:

Any storage device added to a computer beyond the immediately usable main storage is known as "secondary storage". Secondary storage devices are used to store data and programs that are not currently being used by the computer's processor, and can include hard disk drives, solid state drives, external hard drives, USB flash drives, memory cards, and optical storage devices like CDs, DVDs, and Blu-ray discs.

Unlike main memory (RAM), secondary storage devices retain data even when the computer is turned off, and are typically used for long-term storage of files and programs.