ESP8266

An inexpensive Wi-Fi (b/g/n) microchip, the ESP8266, was released in December 2013. It is manufactured by Espressif Systems in China and has a full stack of TC/IP capabilities.

ESP8266 guides

The ESPHome powered multisensor

Building a multisensor is one of the first things you should when starting off with ESPHome. The sensors are cheap, the wiring isn't complicated, and you get your first taste of creating custom firmware for an ESP8266 .