What is a USB Flash Drive?

A Universal Serial Bus (USB) flash drive is a portable memory chip and circuit board contained in a small plastic case about the size of a thumb, giving rise to the name ThumbDrive®. Also called a memory stick, the tiny drive sports a removable cap under which is a USB connector. The chip inside the USB flash drive does not require power to retain data, so batteries are not needed. The drive gets power from the computer, making this memory device a popular choice for transferring files between computers.

Flash drives hit the market in 2000 with capacities of 8 Megabytes (MB), several times greater than the 1.44 MB floppy disks still used at the time. They have become so popular and ubiquitous that models with modest capacities of 128 to 256 MBs are often given away in sales promotions, imprinted for advertising and branding purposes. A 4 Gigabyte (GB) drive can cost as little as $10 US Dollars (USD). Models with the highest storage capacity do tend to be more expensive than buying an equivalent hard drive, however.

The draw of the USB flash drive isn’t capacity alone, but its convenience and portability. Virtually all modern computers feature one or more USB ports and on-board device drivers for recognizing memory sticks, making this storage medium more or less universally accepted. It is also formatted in FAT or FAT32, understood by all modern operating systems from Microsoft® Windows® to Apple® Macintosh® and Linux®. Since USB is a plug-and-play standard, the flash drive can be plugged into a computer and recognized, then removed without needing to reboot the machine.

In some cases, it might be convenient to boot from the memory stick itself, and BIOS settings on most modern motherboards will allow booting from a USB device. A computer user can make a thumb drive bootable by installing appropriate software on it, freely available online. He can also install a portable version of an operating system (OS) on a drive and boot into it, trying it out without having to install it on the computer. A bootable memory stick is termed a Live USB drive.

Special software programs can also be installed on and run from thumb drives. These programs will not store program information in system files on the hard drive like regular software does, making the programs totally portable. Someone can carry an email client with him, for example, to use from anyone’s computer, a Web browser with his bookmarks, or a favorite game.

Chips used in memory sticks have a discrete number of read/write cycles, after which the chip will fail. People who use a USB flash drive to archive copies of important files or to occasionally transfer files probably don't have to worry about this, but if the memory stick is used frequently for running software or is otherwise engaged in regular duty, it could fail within ten years.

Part of what makes the USB flash drive so convenient is also a security risk: the drive is so tiny it is easily lost or misplaced. Information technology (IT) techs might carry one loaded with networking tools on a lanyard or wrist strap to keep it handy. If security is a concern, individuals should consider an encryption program to encode the data on the memory stick. Flash drive with pre-installed security software are available, or people can use one of many encryption tools available online.

The drive weighs next to nothing and is all but impervious to the standard kinds of abuses that might befall a small item like this. It isn’t likely to be effected by being dropped or exposed to extreme temperatures. There are even reports of thumb drives surviving the washer and dryer with no apparent harm done and no data lost. While not wise to count on this, it does speak to the product’s general durability.

Memory sticks are available everywhere electronics are sold. Buying one that is with pre-loaded software typically costs more than purchasing a blank drive.