In most cases, magnetic storage devices refer to hard drives, either internally mounted or external and portable. Inside are a series of magnetic platters, and a read-write head alters the magnetic field to create a one or a zero in binary language.
Some businesses use magnetic tape for data backup. These cartridges resemble videotapes and contain reels of magnetic tape for data storage. The sequential nature of the writing process makes retrieving this data a slow process.
There are still a variety of removable magnetic media devices available, although few of these see regular use. A few manufacturers still produce 3.5 floppy disks, although computers rarely ship with a drive capable of reading these with the rise of more convenient technologies.