USB Flash Disk / USB Drive / USB Flash Drive / USB Disk / USB手指 / 隨身碟

A USB flash drive is a NAND-type flash memory data storage device integrated with a USB (universal serial bus) connector. USB flash drives are typically removable and rewritable, much shorter than a floppy disk (1-4 inches or 25-102 mm), and weigh less than 2 ounces (56 g). Storage capacities typically range from 64 MB to 32 GB or more. Some allow 1 million write or erase cycles and have 10-year data retention, connected by USB 1.1 or USB 2.0 or both. USB Memory card readers are also available, whereby rather than being built-in, the memory is a removable flash memory card housed in what is otherwise a regular USB flash drive, as described below.

USB flash drives offer potential advantages over other portable storage devices, particularly the floppy disk. They are more compact, faster, hold much more data, are more reliable for lack of moving parts, and have a more durable design. Additionally, it has become increasingly common for computers to ship without floppy disk drives. USB ports, on the other hand, appear on almost every current mainstream PC and laptop. These types of drives use the USB mass storage standard, supported natively by modern operating systems such as Windows, Mac OS X, Linux, and other Unix-like systems.

To access the data stored in a flash drive, the drive must be connected to a USB port, either a host controller built into a computer, a USB hub, or some other device designed to access the data, such as an mp3 player with a USB-in port. Flash drives are active only when plugged into a USB connection and draw all necessary power from the supply provided by that connection. Some flash drives, however, especially high-speed drives, may require more power than the limited amount provided by a bus-powered USB hub, such as those built into some computer keyboards or monitors. These drives will not work unless plugged directly into a host controller (i.e., the ports found on the computer itself) or a self-powered hub.