A physical material in which a computer saves the information, data and instructions is called storage medium. The capacity of the storage media can be defined in terms of the number of characters or bytes that it can store.
A computer hardware that retrieves few items from the storage media or records some items to the storage media is called a storage device. The process of transmitting the items in to the storage medium from the memory is called as writing and the process of transmitting the items into the memory from the storage medium is called reading.