What is a USB flash drive?

A USB flash drive (UFD) is a compact portable device used to store data. It pairs a USB (Universal Serial Bus) interface with a flash memory data storage unit. The USB flash drive is also known as memory stick, key drive, jump drive, or simply USB drive. The shape typically resembles a human finger or thumb, hence also the name thumb drive.

Technically, a UFD is not a drive because the flash memory technology is purely digital, meaning it does not contain any moving parts. Flash memory is non-volatile, i.e. it does not need power to maintain the stored information. On the one hand, these characteristics make flash drives less prone to physical damage and on the other hand they are perfectly silent. The term flash indicates that blocks of data are erased and reprogrammed in a flash, rather than deleting them one byte at a time.