As with all technology, USB technology will evolve over time. In the 18 years of marketing, USB has derived a variety of versions, each version of the connecting line and read and write speed are not the same, can be described as very confusing.
A few years later, the market is likely to appear in a standardized, unified USB completely replace the existing complex USB line. And in the wait-and-see type-C future, we might wish to review the development history of USB, understanding past technology standards and pending overcome technical obstacles.

If you have used a computer for more than a decade ago, it's very easy to understand USB. Although its technical parameters and connection speed is still complex, but the USB technology is still evolving.
Before the birth of the USB Pentium and Pentium two generation era, all the data interface of the computer is very large (and now the contrast can really use "great" to describe). Connect a mouse? Then you need a PS/2 or serial interface. Similarly, the keyboard is also the same, or apple Desktop, DIN interface. Printer and scanner is generally used old parallel interface, and if you do not want to use the SCSI can also be use to connect to external memory. In addition, the computer is connected to the game handle or joystick is usually required a game interface, and in the 90's, the interface is only independent sound card.
Thus, the problem of computer interface is very obvious. One of them needs to take up a large space for special development cards, and when the fault occurs, the problem is also very troublesome investigation. By the end of the 90's, people began to add a pair of USB interface to the computer - usually behind the fuselage - this is the common USB 1.1 interface, the maximum speed of up to 12Mbps. Initially, the accessory manufacturer did not change all the interface to USB, but the mouse, keyboard, printer, other accessories have been the first to use, and then shortly after USB was as the main interface.
In the early twenty-first Century, the USB 2 interface began to gradually spread, and began to replace many of the original things. First of all, the USB flash memory has eliminated the floppy disk, and also makes the disc media gradually fade - when the compact U disk can be qualified for all external storage, why use CD or DVD to serve as a storage container and operating system of the installation disk? In addition, USB 2.0 also let the computer connecting peripherals to become feasible -- the such as WiFi adapter, disk drives, Ethernet interface and so on -- in the past, these are all need the fuselage built-in installation. 480Mbps's transmission speed makes it possible, and by this time, the USB interface is starting to completely replace the old interface on the desktop and notebook (especially laptop).