What Is USB
USB is by far the most common external computer port in use today and every modern computer provides multiple USB ports for connecting anything from mice and keyboards to USB pen drives and other hardware. USB stands for "Universal Serial Bus" and it was introduced in 1996 and has since become the industry standard external interface. Most external hardware uses the USB interface and there are around 2 billion USB devices being sold every year. USB ports are found not only on desktop and laptop computers; they're found on video gaming consoles, in-car entertainment systems, portable devices, televisions and various other hardware.
USB is currently up to the third revision, introduced in 2008. USB 3.0 is up to ten times faster than its predecessor, USB 2.0 which, in turn, was much faster than USB 1.0. In spite of USB 1.0 being released in 1996, it was not until 1998 that the USB 1.1 standard became the first widely-adopted version. USB devices are all backwards compatible. If, for example, you connect a USB 3.0 hard drive to a USB 2.0 port, you'll still be able to use it, although not at the maximum transfer speed supported by the hard drive.
USB has done away with most of the older interfaces. Previously, for example, mice and keyboards used PS/2 ports which are steadily being phased out altogether. Most newer computers and motherboards still provide one PS/2 port, but more and more devices lack them altogether. The same is true of the parallel port which was previously used for printers and scanners. Virtually all modern printers and scanners now use USB ports instead.
Another common application for USB ports is storage devices. USB flash drives, also known as pen drives, are widely used as a way to easily back up and transfer data between different computers and devices. Modern computers can even boot up from USB pen drives, allowing you to install operating systems and software from them. This is especially useful in compact laptop computers and netbooks which don't usually have an optical drive.
There are various types of USB cables allowing you to connect different devices to your computer or other device. Smartphones and other portable devices, for example, have smaller connectors due to space restrictions.