There is a wide variety of hardware that can be connected to the internet. More precisely, nearly every device can be connected to the internet,although not by default, but sensors can be added at any time. The most generic and most often used IoT devices are the Raspberry Pi, the BeagleBone and the Arduino  . All of these small computer or controllers are designed to be small, lightweight and to consume as little electricity as possible while providing a reasonable performance. The market for such devices has become very large and there are countless hardware extensions, sensor types and special software designed for the internet of things available at a generally low price.