The term platform means that Arduino includes a lot of things which all work together to provide an amazing practical learning experience. The most common thing people think of when thinking about the word Arduino is the physical boards, such as the Arduino UNO, and the Arduino Nano (both based on the popular ATmega238p microcontroller by Microchip). However, Arduino also means the software environment used to program the devices. Finally, it can also refer to the "modules" which can be plugged into an Arduino to enhance its capabilities, commonly known as shields.