A very successful platform used for the Internet of Things
The ESP8266 WiFi Shield is an Arduino compatible shield for the ESP8266 WiFi SoC – a leading platform for Internet of Things (IoT) or WiFi-related projects. The ESP8266 WiFi Shield finds a middle ground between the Module and the Thing that provides a great introduction to the ESP8266 – without leaving the comfortable hardware confines of your Arduino.
The ESP8266 WiFi Shield comes pre-flashed with an AT-command firmware, so it can be controlled by any UART, but it also breaks out and provides command access to all of the ESP8266’s I/O. Additionally, the ESP8266 WiFi Shield can be repurposed and reprogrammed through the programming port found on the top-right side of the shield.