A USB (Universal Serial Bus) key is a small memory chip which acts as a portable storage device
. It can be used for transfer of data or to store information offline until it is needed again. It has got built in USB interface and easily plugs into the USB socket of PC. USB key is also otherwise known as flash drive or key chain drive.
USB key is rewritable and since it has less moving parts it is very much durable and reliable. Hence, it has become popular within very short time and has replaced floppy disk, Zip drive disk and Compact Disk etc. For its power requirements it does not need battery. It rather gets its power from the USB connection itself.
USB Keys first came into market in 2000 and was commercially launched by IBM and Trek Technology. At that time its storage capacity was limited to just 8 Mb. But since then they have come a long way. Modern and fastest flash drives use dual channel controller. These are a cheap, robust and small in size because of which various manufacturers have tried to integrate them in various common day items such as watches, pens etc. or are combined with functions of digital audio players.
However, USB flash drive has certain drawbacks. Its write and erase cycles are limited. Write-protect mechanism is also not present in most of the USB keys. If the data USB key contains is sensitive then its getting lost or misplaced due to small size also poses a big problem.