Announced in 2005, the Arduino is a single-board microcontroller. The hardware itself consists of an open-source hardware board designed around an 8-bit Atmel AVR microcontroller. The project was started for students at the Interaction Design Institute Ivrea, in Ivrea, Italy.
In a nutshell, the Arduino is an open-source physical computing platform. It’s based on a single-board microcontroller board, and a development environment for writing software. It can be used to develop interactive objects. For example, it can be used with switches or sensors to control lights or other physical outputs. This makes the board a favorite for ‘do-it-yourself’ types that love the challenge of building projects from scratch.
In comparison to other single-board computers out there, Arduino is relatively inexpensive. Pricing is usually around $30, and ‘knock off’ clones can be found from $5 - $10. Even the pre-assembled modules cost no more than $50. The board runs on Windows, Mac OSX, and Linux. The programming environment is clean and simple, and perhaps most importantly easy to use for beginners. On top of it all, both the hardware and software are open source.
Starter kits, accessories, shields, and a whole lot more are all available from the official Arduino store online.