Arduino® is an open source do-it-yourself platform for electronics projects, and Arduino® boards are the basis of any Arduino® project and can be purchased at a moderate price from a variety of manufacturers or made at home with electronic components and a soldering iron. These boards come in a variety of sizes, shapes, and costs, suitable for different projects. By early 2010, there were more than a dozen standard Arduino® boards.
The standard board for beginners learning Arduino® is the Arduino® Uno. Like several other Arduino® boards, the Uno provides a USB interface to a computer. The interface is used to program the board. Although this board is a basic beginner's board with few built in features, it comes equipped with an interface allowing the user to attach an Arduino® shield, which can add numerous additional features to the board.
In some instances, USB communication is not an option. For example, a project may require an Arduino® board to be concealed inside a children's toy but still communicate with other devices. Alternatively, an Arduino® invention may need to be reprogrammed without removing it from a waterproof casing. In these cases, Arduino® Bluetooth (BT) boards or Arduino® Fio boards are very usable. The Arduino® BT uses a specific interface while the Arduino® Fio uses an XBee radio and provides an easy way to recharge its batteries.
One of the more unusual Arduino® boards is called the Arduino® Lilypad. The Lilypad is a small round board that can be sewn into fabric and attached to various sensors that allows programmers to create wearable electronic devices. An example of a Lilypad project would be a jacket with LED lights that automatically activated in the dark or under any other conditions determinable by sensors. Unlike the Arduino® Uno and Arduino® BT boards, the Lilypad cannot connect to an Arduino® shield.
Arduino® Mini and Arduino® Nano boards are used for applications where there is limited space. Both of these boards are very small. The mini uses a mini USB connection for its Ardino interface. The Nano uses a full size USB port.
There are also a variety of Arduino® boards available for advanced users. Two that are specifically designed for experts are called the Arduino® Pro and Arduino® Pro Mini boards. These boards are more powerful and flexible than ordinary Arduino® boards but require some extra work on the part of the builder.