Removable storage, in computing terms, is any form of data storage which is not incorporated into the computer itself. In addition to providing a form of backup by removing data from a centralized computer system, it is also much more portable than an entire computer, allowing people to easily carry data back and forth from a wide variety of locations.
In earlier days of computer, punch cards and magnetic tape were the operating methods of removable storage. Punch cards have been used to store data for centuries, but were especially well suited to computing because they lent themselves well to storing data in a binary form. Magnetic tape was the next step from punch cards, allowing computer users to store more data on a more quickly written medium. Ironically, punch cards are actually a more stable form of removable storage than magnetic tape, which can easily be corrupted.
As computers became more widespread, floppy disks and compact discs (CDs) became a more widely used form of removable storage. Both had larger capacities than earlier methods, and companies constantly struggled to manufacture disks with a larger capacity as computers generated files of ever greater size. While earlier compact storage was measured in kilobytes, later forms were able to store much larger files: most CDs, for example, can store data measured in megabytes.
Another form of compact storage takes the form of removable hard drives and flash drives. Flash drives are also known as memory sticks or USB sticks. Both types of removable storage can store gigabytes of data, and can be written to very quickly through a Universal Serial Bus (USB) port. Some manufacturers make removable hard drives which can connect to FireWire, Small Computer System Interface (SCSI), or parallel ports, although the majority take advantage of USB technology.
The wide range of options in the field of removable storage allows users to select the technology which works best for them. Disks are very useful for temporary storage, or sending data to other locations, and are frequently used by graphic designers to literally mail large files, rather than attempt to transfer very large files over an Internet connection. Many companies also use disks for backup, although this practice has been called into question due to the long-term instability of these storage methods. Many consumers prefer removable hard drives or flash drives for the rapid exchange of data between multiple computers, and the easy portability: many flash drives, for example, can fit on a keychain.