USB has become the most common method to connect external devices to computers and has essentially replaced earlier interfaces such as
parallel and serial ports. USB has several advantages for computer to device interconnections. A USB connector is essentially foolproof. Unlike
other device interfaces, there are no pins to bent or misalign.
In addition, the USB computer port can supply a small amount of power to the connected
device. This allows manufacturers to forgo the usual power brick for low power devices and also reduces the cost of the product.
Most modern operating systems such as Windows, Linux and UNIX have built in device driver software to accomodate USB devices. However, specialized USB devices
will still require device specific software to allow full functionality.
At present, USB interfaces can operate at one of 3 speeds, commonly designated as USB 1.0, USB 2.0 and USB 3.0. Fortunately, higher speed devices and ports
automatically fall back to whatever speed the port or device is capable of accomodating. The newest USB 3.0 specification allows for data transfer at speeds
up to 5 gigabits per second. However, in practice the speed is usually limited by the physical device to significantly lower speeds.