Removable Storage

Removable storage has been around almost since the computer began. Early removable storage was based on magnetic tape like that used by an audio cassette. Before that, some computers even used paper punch cards to store information!
There are many different types of removable storage. CD Burners, CD-ROM Drives, DVD Burners, DVD Drives, Enclosures, Flash Media Readers, Floppy Disk Drives, Removable Drive Trays, and Tape Drives. 

Modern removable storage devices offer an incredible number of options, with storage capacities ranging from the 1.44 megabytes (MB) of a standard floppy to the upwards of 20-gigabyte (GB) capacity of some portable drives.

Magnetic Storage
The most common and enduring form of removable-storage technology is magnetic storage. For example, 1.44-MB floppy-disk drives using 3.5-inch diskettes seem to have been around forever and they just aren't used anymore. Hard Drives are magnetic storage, too, and they are still used sometime.

USB Flash
The little dongles you can buy at your neighborhood drugstore are great. They are super cheap, ultra-portable and act just like a hard drive. These are probably going to become the most popular type of removable media very soon if not already.