Arduinos are mini computers on a circuit board designed primarily for controlling electronic circuits. They have analog and digital inputs and outputs that allow them to input data and turn things on and off. For some applications (like building a robot), no direct interface with humans, such as a keyboard or display screen, is necessary. For some applications, however, you will want to display information and also input commands. For example, you may be designing a sensor device to monitor sensor readings (tricorder, anyone?). In this case, you will want to have a display. You may also want...