What is a microcontroller? The easiest way to understand what is a microcontroller is to think about a tiny computer: it includes a processor, memory and input/output (I/O) peripherials to connect small display, buttons, motors, sensors, etc. To “control” a microcontroller, you can put programs onto it and run them. As we will see later in this lesson, we usually write programs using a laptop and then transfer the programs into the microcontroller to execute it. A microcontroller can look like this: i.e. very much like what we call an “ integrated circuit ”. Look for instance at what we see when we zoom in the previous picture: A typical microcontroller includes a processor, memory and input/output (I/O) peripherals. What is an ESP8266? ESP8266 architecture An ESP8266 is a microcontroller: Low-power, highly-integrated Wi-Fi solution A minimum of 7 external components Wide temperature range: -40°C to +125°C ESP8285 — 8 Mbit flash embedded Source : https://www.espressif.com/en/products/