Storage drives connected by USB devices known otherwise as flash drive, USB stick, USB key and thumb drive. Also includes larger storage devices such as portable hard drives. USB drives are storage drives connected by USB (Universal Serial Bus) to the computer. A USB drive -- also known as a flash drive or keychain drive -- is a plug-and-play portable storage device that uses flash memory and is lightweight enough to attach to a key chain. Above the OS level, work with these drives does not differ much from the work with the fixed drives: they can be partitioned and partitions can be formatted OS-supported filesystems. Such drives can also be bootable. Developers may use this capability to test new operating system without installing it, or to gain access to non-encrypted fixed hard drive if the main operating system does not boot any longer.