Since the release of the USB V0.7 version on November 11, 1994, the USB version has undergone years of development and has evolved into version 3.1, becoming the standard expansion interface for computers in the 21st century. Currently (2016), the motherboard mainly uses USB2.0 and USB3.0 interfaces, and each USB version can be well compatible. USB uses a 4-pin (USB 3.0 standard 9-pin) plug as a standard plug. It can be daisy-chained to connect all peripherals, and can connect up to 127 external devices without losing bandwidth. USB requires support from the host hardware, operating system, and peripherals to work. The motherboards of the 21st century generally use a control chipset that supports USB functions. The motherboard also has a USB interface socket, and in addition to the socket of the backplane, a USB pin is reserved on the motherboard, which can be connected through a connection. To the front of the chassis as a front USB interface for ease of use (note that you should carefully read the motherboard manual and connect as shown in the wiring, do not connect the wrong and make the equipment damaged). Moreover, the USB interface can also realize two-machine interconnection through a dedicated USB connection line, and can expand more interfaces through the Hub. USB has the advantages of fast transmission speed, convenient use, hot plugging, flexible connection, independent power supply, etc. It can connect mouse, keyboard, printer, scanner, camera, charger, flash drive, MP3 player, mobile phone, digital camera, mobile Hard disk, external optical drive / floppy drive, USB network card, ADSL Modem, Cable Modem, etc., almost all external devices.
In theory, the USB interface can be used to connect up to 127 peripherals such as mice, modems and keyboards. Since its introduction in 1996, USB has successfully replaced serial and parallel ports, and has become one of the must-have interfaces for personal computers and a large number of smart devices in the 21st century.