USB

Universal Serial Bus (USB) is a serial bus standard to connect devices to a host computer. USB was designed to allow many peripherals to be connected using a single standardized interface socket and to improve plug and play capabilities by allowing hot swapping; that is, by allowing devices to be connected and disconnected without rebooting the computer or turning off the device. Other convenient features include providing power to low-consumption devices, eliminating the need for an external power supply; and allowing many devices to be used without requiring
USB supports following signaling rates:
A low speed rate of 1.5 Mbit/s is defined by USB 1.0. It is very similar to "full speed" operation except each bit takes 8 times as long to transmit. It is intended primarily to save cost in low-bandwidth human interface devices (HID) such as keyboards, mice, and joysticks.
The full speed rate of 12 Mbit/s is the basic USB data rate defined by USB 1.1. All USB hubs support full speed.
A hi-speed (USB 2.0) rate of 480 Mbit/s was introduced in 2001. All hi-speed devices are capable of falling back to full-speed operation if necessary; they are backward compatible. Connectors are identical.
A SuperSpeed (USB 3.0) rate of 5.0 Gbit/s. The USB 3.0 specification was released by Intel and partners in August 2008, according to early reports from CNET news. The first USB 3 controller chips were sampled by NEC May 2009 [8] and products using the 3.0 specification are expected to arrive beginning in Q3 2009 and 2010.[9] USB 3.0 connectors are generally backwards compatible, but include new wiring and full duplex operation. There is some incompatibility with older connectors.