Since delivery of the first vacuum-column magnetic-tape transport in 1953 and the first movable-head disk drive in 1957, tape and disk devices in many configurations have been the principal means for storage of the large volumes of data required by data processing systems. Magnetic drums and other device geometries have also been important system components, but to a lesser extent. Over the past twenty-five years significant developments have been made that increase the capacity, reduce the cost, and improve the performance and reliability of these devices. With each improved device the range and nature of the applications undertaken have expanded and, in turn, led to a need for further device improvement. This paper gives a general review and historical perspective of magnetic storage development within IBM and is an introduction to the subsequent papers on disk, diskette, and tape technology and on disk manufacturing.