Universal Serial Bus (USB) is an industry standard developed in the mid-1990s that defines the cables, connectors and communications protocols used in a bus for connection, communication, and power supply between computers and electronic devices.
USB was designed to standardize the connection of computer peripherals (including keyboards, pointing devices, digital cameras, printers, portable media players, disk drives and network adapters) to personal computers, both to communicate and to supply electric power. It has become commonplace on other devices, such as smartphones, PDAs and video game consoles.USB has effectively replaced a variety of earlier interfaces, such as serial and parallel ports, as well as separate power chargers for portable devices.
In general, there are four basic kinds or sizes related to the USB connectors and types of established connections:
1.the older “standard” size, in its USB 1.1/2.0 and USB 3.0 variants (for example, on USB flash drives)
2.the “mini” size (primarily for the B connector end, such as on many cameras)
3.the “micro” size, in its USB 1.1/2.0 and USB 3.0 variants (for example, on most modern cellphones)
4.the versatile “USB On-The-Go” scheme, in both mini and micro sizes.