An Arduino® shield is a small electronic board that can be attached to some Arduino® boards in order to extend their functionality by adding additional hardware. Arduino® is a popular open source electronics platform designed to be accessible to beginners but is still useful for advanced and professional users. An Arduino® shield is especially helpful for beginners who may not feel comfortable soldering their own components but still want to add additional components to their Arduino® inventions. Arduino® Shields can be stacked, making very easy to combine two or more for a project that needs to have several additional components. More than two hundred Arduino® shields have been produced by numerous manufacturers.
Like Arduino® boards, Arduino® shields are widely available and affordable for electronics hobbyists. The vast number of different Arduino® shields means that not all shields will be available in all areas. Hobbyists have also found that software support for more obscure boards is often far less complete than for more mainstream Arduino® components.
One of the more popular Arduino® shields is the Xbee Shield. This Arduino® shield attaches a low-power radio to an Arduino® device, allowing it to send signals over distances of up to 300 feet (about 100 meters). One example of this shield is a wireless weather station which automatically reports if outside weather conditions, such as temperature and barometric pressure, exceed pre-defined limits. There is also an Arduino® board that uses an Xbee radio as its ordinary interface, eliminating the need for the Arduino® shield.
Another popular Arduino® shield is the motor shield which allows an Arduino® device to easily control DC motors. This is very useful for robotics projects where the device will move around on its own or just needs to operate a motor to complete a specific task. Arduino® is a very popular platform for robotics, so this shield is used frequently.
Many Arduino® shields are designed to improve the Arduino® device's communication abilities. The Arduino® LCD Shield allows the device to interface with a simple character LCD screen. This interfacing allows Arduino® devices to easily display human readable information, such as sensor output or error messages. For communicating with computers and cell phones, there are also shields that utilize either Bluetooth or WiFi technology. Projects that need high speed connections to computers or networks can use the Arduino® ethernet shield, which provides the Arduino® device with a wired network interface.