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 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. USB drives with USB 2.0 support can also be faster than an optical disc drive, while storing a comparable amount of data in a much smaller space.
A flash drive consists of a small printed circuit board typically in a plastic or metal casing and more recently in rubber casings to increase their robustness. This makes the drive sturdy enough to be carried about in a pocket, for example as a key fob, or on a lanyard. Only the USB connector protrudes, and it is typically protected either by a removable cap or by retracting into the body of the drive. Most flash drives use a standard type-A USB connection allowing them to be connected directly to a port on a personal computer.
