Secondary storage

Secondary storage refers to all forms of data storage other than main memory; data in secondary storage generally had to be brought into main memory before it can be operated upon.

Over time there have been many forms of secondary storage: magnetic tape is one of the oldest, and is still in use today. Disks are almost as old, and again, still in use (although the rise of solid state mass storage such as SD memory cards may make them obsolete).

There are a number of types which are now obsolete: punched cards, paper tape, etc.