USB flash drives are NAND-type flash memory data storage devices integrated with a USB interface. They are typically small, lightweight, removable and rewritable. Memory capacity typically ranges from 8 megabytes up to 64 gigabytes or more. They are limited only by current flash memory densities. As capacity increases, so does price.

In 1998 the USB flash drive was first invented by Dov Moran. Dan Harkabi led the development and marketing team at M-Systems by which the first USB flash drive was made. His most significant contribution was that the product can be self-reliant and installations of drivers are not needed. Nearly simultaneous development of similar products was undertaken at Netac and at Trek 2000, Ltd too. All three companies have similar and disputed patents.

IBM was the first North American seller of a USB flash memory drive, and marketed an 8 MB version of the product in 2001 under the "Memory Key" nickname. IBM later introduced a 16 MB version manufactured by Trek 2000, and returned to M-Systems for the 64 MB version in 2003. Lexar can also lay claim to a USB flash drive product. In 2000 they introduced a Compact Flash (CF) card having an internal USB function. Lexar offered a companion card reader and USB cable that eliminated the need for a USB hub.

The first USB flash drive was made by M-Systems and distributed in Europe under the "disgo" brand in sizes of 8 MB, 16 MB, 32 MB and 64 MB. These were marketed as "a true floppy-killer," represents the end of using a floppy and this design was continued up to 256 MB. Asian manufacturers soon started making their own USB flash drives that were cheaper than the Disgo series, such as PQI and A-DATA, etc.

Modern USB drives have USB 2.0 connectivity. However, they do not currently use the full 480Mbit/s the specification supports due to technical limitations inherent in NAND flash.

Nowadays there are not only different in capacity of USB flash drives, but also diversiform appearance of them. It’s not surprising at all to see a novelty USB flash drive that looks like a piece sushi or an animal.