The ESP8266 chip is a SoC (system on a chip) and powerful microcontroller with built-in Wi-Fi receiver. In addition, this microcontroller is relatively cheap compared to others. With this chip you have everything you need to get started with Wi-Fi at a cheap price.
Application of the ESP8266
Specially designed to connect to the Internet, the ESP8266 microcontroller has everything you need to help you do just that. This chip is perfect for DIY IoT & home automation projects. The ESP8266 can be used using the AT command firmware or by connecting it to a microcontroller.
ESP8266; an Arduino replacement
Many novice technicians start with the hardware and software of Arduino. It offers an easy entry into the world of microcontrollers and technology. Compared to Arduino, the ESP8266 is a lot more extensive and therefore less suitable for the beginner. This does not have to be a barrier, there are many manuals available online. This way everyone can learn how to use the ESP8266.
The ESP8266 is sometimes sold as a WiFi shield for Arduino, but this really diminishes the capabilities and power of the ESP. For most projects, with an ESP8266 you no longer even need an Arduino.
ESP8266; Raspberry Pi and WiFi
With an ESP8266 it is possible to affordably add a Wi-Fi module to your microcontroller. An example project of what you can create with an ESP8266 is to use it on your Raspberry Pi RP2040 as an MCU to control the I/O pins.
NodeMCU or Wemos
Two popular Arduino controllers with ESP8266 are the NodeMCU and Wemos. These Wi-Fi compatible controllers are suitable for IoT projects and can be easily connected to the internet thanks to the ESP.
Differences between ESP8266 and ESP32
The difference between the ESP32 and ESP8266 is the lack of Bluetooth in the ESP8266. The ESP32 has further developed the technology of the 8266. You could say that the ESP8266 was a predecessor of the ESP32.