Arduino is an open-source platform used for building electronics projects. Arduino consists of both a physical programmable circuit board (often referred to as a microcontroller) and a piece of software, or IDE (Integrated Development Environment) that runs on your computer, used to write and upload computer code to the physical board.
The Arduino platform has become quite popular with people just starting out with electronics, and for good reason. Unlike most previous programmable circuit boards, the Arduino does not need a separate piece of hardware (called a programmer) in order to load new code onto the board — you can simply use a USB cable. Additionally, the Arduino IDE uses a simplified version of C++, making it easier to learn to program. Finally, Arduino provides a standard form factor that breaks out the functions of the micro-controller into a more accessible package.

A microcontroller board based on the ATMega328 from Atmel.
This board contains all the key features to ensure you can start programming quickly and easily.

This board features:
• 14 digital I/O interfaces (6 of which can be used as PWM output)
• 6 analogue inputs
• 16 MHz crystal oscillator
• USB port
• Power supply
• ICSP header
• Reset
• DIP/DIL version

Technical data:
• ATMega328
• Operating voltage: 5 V
• Input voltage: 7 – 12 V
• Input voltage (limit): 6 – 20 V
• Digital inputs/outputs: 14
• Analogue inputs: 6
• DC current 40 mA (I/O)/50 mA (3.3 V)
• Flash memory: 32 KB
• SRAM: 2 KB
• Clock speed: 16 MHz