Historically, "memory" referred to "magnetic core memory" in the 1950s, and then to semiconductor-based storage in the 1970s, at a time when the fastest response times were for magnetic core, and then for semiconductor memory, respectively. The evolution of usage can be glimpsed in the history of computing hardware, as the costs of the various technologies declined.
Each type of storage is suited for different purposes, and most computers contain several types: primary, secondary, and volatile.
Secondary storage, also known as peripheral storage, is where the computer stores information that is not necessarily in current use. It is typically slower and higher-capacity than primary storage. It is almost always non-volatile.
Confusingly, these terms are often used differently. Primary storage can be used to refer to local random-access disk storage, which should properly be called secondary storage. If this type of storage is called primary storage, then the term secondary storage would refer to offline, sequential-access storage like tape media.
Random-access media has the property of accessing any portion at any time. Semiconductor memory (RAM) and magnetic disk are examples of this type of storage.
In disk storage, these are the two primary access methods. Block access means that the disk is divided into normally equal-sized blocks which are accessed at random by the operating system. File access contains an abstraction of files and directories which can be used to refer to storage content. Another access method, content-addressable storage (CAS) uses a hashing algorithm to refer to pieces of data.
