USB
USB (Universal Serial Bus) is currently the most commonly used connector to connect various things to computers, replacing what used to be a great profusion of serial, parallel, and other connectors used to attach printers, keyboards, mice, and other peripherals and devices. It is also widely used for charging batteries of mobile devices, replacing another profusion of proprietary connectors that used to be used (and is still sometimes used, for instance with Apple replacing the proprietary iPhone connnector with another proprietary iPhone connector not compatible with the old one).
USB may get even more useful in the future, as a revision of the standard will make it possible to use higher wattages of power through USB, leading to it being a possible replacement for old-fashioned electric outlets for many purposes (getting around the confusing variety of outlet types in different countries), and increasing the use of direct current instead of the alternating current which has dominated for over a century.
The increasing number of things that connect to USB ports has resulted in new models of computers generally having increasing numbers of spots to plug them in, and often other devices such as monitors will have a few more. People still keep running out of them, so expansion plug units are popular as well.
A number of versions of the USB standard have been released, with 3.1 being the latest.
