Pieter P, wrote a sequel to his popular Beginner’s Guide to Arduino, focusing on the ESP8266, a $3 Wi-Fi board with endless possibilities. The tutorial covers topics ranging from setting up the hardware and installing software to wirelessly controlling RGB lighting and receiving email notifications. The ESP8266, manufactured by Espressif, is a SoC with a 32-bit MCU and Wi-Fi transceiver, allowing for programming like an Arduino while also enabling Wi-Fi communication. Different ESP8266 modules and development boards are available, each with unique features. Programming the ESP8266 using the Arduino IDE is covered, but other options like using the official SDK or flashing with LUA or Python are mentioned. Basic knowledge of microcontrollers is recommended before diving into the ESP8266-specific details highlighted in this guide.
https://tttapa.github.io/ESP8266/Chap01%20-%20ESP8266.html