The Arduino Nano USB (Universal Serial Bus) Microcontroller is a breadboard ready version of the Arduino mini with integrated USB (Universal Serial Bus) The Nano has more analog input pins as compared to most Arduino boards & an onboard +5V AREF jumper. The Nano automatically senses & switches to the higher power power supply, so there is no need for a power select jumper Arduino Nano is a complete & breadboard friendly Arduino board. It has everything that Arduino UNO/ Duemilanove has (electrically) with more analog input pins & relatively smaller size Arduino Nano is a surface mount breadboard embedded version with integrated USB (Universal Serial Bus). It is a small, complete, & breadboard friendly. It has everything that Diecimila/ Duemilanove has (electrically) with more analog input pins & onboard +5V AREF jumper. Physically, it is missing the power jack. The Nano will automatically sense & switch to the higher voltage source of power, there is no need for the power select jumper. Nano's got the breadboard-ability of the Boarduino & the Mini+USB with smaller footprint than either, so users have more breadboard space. It