Any AVR microcontroller based board which follows the standard Arduino schematic and is flashed with the Arduino boot-loader can be called an Arduino board. The Arduino is an easy prototyping platform in which the hardware is very simple to use and to be connected with any other system. The programing environment is also very easy to start with and has lot of built-in functions for every simple and complex task. The output or inputs can be taken from the boards or given to the board using convenient connectors. Both digital and analog inputs and outputs are available in all Arduino boards. The Arduino boards can also communicate with other devices using standard communication ports like USART, IIC, and USB etc. The Arduino board also provides pins which can be used as external hardware interrupts pins.