The Arduino Nano is a small, complete, and breadboard-friendly board based on the ATmega328 (Arduino Nano 3.x). It has more or less the same functionality of the Arduino Duemilanove, but in a different package. It lacks only a DC power jack, and works with a Mini-B USB cable instead of a standard one.
Specifications
Microcontroller
ATmega328
Operating Voltage
5 Volt
Input Voltage
7-12 Volt
Digital I/O Pins
14 (of which 6 provide PWM output)
Analog Input Pins
8
DC Current per I/O Pin
40mA
Flash Memory
32 KB (ATmega328) of which 2 KB is used for the bootloader
SRAM
2 KB (ATmega328)
EEPROM
1 KB (ATmega328)
Clock Speed
16 MHz
Other Arduino Nano Boards
If you are looking for a Nano board with similar functionality but also provide additional features, check:
The Arduino Nano can be powered via the Mini-B USB connection, 6-20V unregulated external power supply (pin 30), or 5V regulated external power supply (pin 27). The power source is automatically selected to the highest voltage source.
Download the latest Arduino IDE
The open-source Arduino Software (IDE) makes it easy to write code and upload it to the board. This software can be used with any Arduino board.
The Arduino Leonardo is a microcontroller board based on the ATmega32u4. It has 20 digital input/output pins (of which 7 can be used as PWM outputs and 12 as analog inputs).