Last modified on 23 June 2016, at 15:01

Universal Serial Bus (USB) is a high speed serial bus used to interface computers and other devices. USB allows plug and play connections (that is devices can be connected and disconnected with minimal configuration on the part of the user, and without the need to restart the host computer) between devices such as modems, digital cameras, hard drives, keyboards and mice. The standard is supported by a number of large computer manufacturers including Apple Inc., Hewlett-Packard, Intel, Microsoft and NEC.
The current USB Standard is 3.1, which has a theoretical transfer rate of about 10GB per second. Version 3.1 is, like past versions, theoretically backwards compatible, though, so older styles re sill usable in modern computers. There are also two types of USB-- type A and Type B. Type B is not as common, but is used for some devices such as printers and hubs. Type A is used for almost everything else, some of which are listed above. Perhaps the best-known Type A devices are USB Flash Memory drives.
USB Mass Storage "Flash Drives" are small, removable, rewritable and have nearly completely replaced floppy disks. As the cost of memory decreases the capacity of the drives increases. Such drives have usage in some MP3 Players, such as the iPod nano, or in computer systems administration or repair in addition to data storage and transfer.

Unlike some other forms of data connections, USB cables allow a peripheral device to be powered from the main device or computer. However, when the main device is a laptop, its power-saving strategy may cut off power to the peripheral device unexpectedly. As a result, powered USB hubs can be used that draw power from a separate electrical outlet rather than the host computer. USB cables then connect one or more peripherals into the hub and the hub to the host computer.


Version Theoretical Speed Release Date Notes
0.8 December 1994
0.9 April 1995
0.99 August 1995
1.0 January 1996[1]
1.1 1.5 Mb/s (Low Bandwidth) or 12 Mb/s (Full Bandwidth) August 1998
2.0 480 MB/s April 2000[1]
3.0 4.8 GB/s[2][3] November 2008
3.1 10GB/s January 2013 Sometimes called "3.1 Gen 2"[4]


USB Implementers Forum [1]