Types of USB Connectors
Currently, there are four types of USB connectors: Type A, Type B, mini-A and mini-B and are supported by the different USB specifications (USB 1, USB 2 and USB-OTG).  USB A (Host)
Often referred to as the downstream connector, the Type A USB connector is rectangular in shape and is the one you use to plug into the CPU or USB hub.
 USB B (Device)
Also called the upstream connector, the Type B USB connector is more box-shaped and is the end that attaches directly to the device (such as a printer or digital camera).
USB 1.1 specifies the Type A and Type B.  Mini-B
The USB 2.0 connector was too large for many of the new handheld devices, such as PDAs and cell phones. The mini-B was introduced to enable consumers to take advantage of USB PC connectivity for these smaller devices.
USB 2.0 specifies the Type A, Type B and mini-B.  Mini-A
With the need to connect mobile devices without the aid of a computer, the mini-A port was designed to connect the new generation of smaller mobile devices.
USB OTG specifies the mini-A. Certified Wireless USB
With an estimated 2 billion plus USB connected devices in the world and a growing interest in wireless computing, it's no surprise that development has turned to wireless USB. The USB Implementers Forum has introduced Certified Wireless USB the newest extension to the USB technology. Wireless USB applies wireless technology to existing USB standards to enable wireless consumers to still use USB devices without the mess of wires and worry of cords. Still in its infancy, the Wireless USB specifications were made available to the public only in May 2005. Wireless USB is based on the WiMedia MAC Convergence Architecture, using the WiMedia Alliance's MB-OFDM ultra wideband MAC and PHY. It delivers speeds equivalent to wired Hi-Speed USB, with bandwidths of 480Mbs at 3 meters and 110 Mbs at 10 meters.
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