A USB flash drive is a flash memory data storage device integrated with a USB interface. USB flash drives are typically removable and rewritable and weigh less than 60 grams. Some allow 1 million write or erase cycles and have 10-year data retention.
Compared to older storage facilities USB flash is more compact, faster, hold much more data, have a more durable design, and are more reliable for lack of moving parts. Nothing actually moves in a flash drive: it is called a drive because it is designed to read and write data using the same system commands as a mechanical disk drive.
A flash drive consists of a small printed circuit board protected inside a plastic, metal, or rubberised case, robust enough to be carried with no additional protection, in a pocket or on a key chain for example. The USB connector is protected by a removable cap or by retracting into the body of the drive, although it is not liable to be damaged if exposed.