ESP8266 is a highly integrated chip designed for the needs of a new connected world. It offers a complete and self-contained WiFi networking solution, allowing it to either host the application or to offload all WiFi networking functions from another application processor.
ESP8266 has powerful on-board processing and storage capabilities that allow it to be integrated with the sensors and other application specific devices through its GPIOs with minimal development up-front and minimal loading during runtime. Its high degree of on-chip integration allows for minimal external circuitry, and the entire solution, including front-end module, is designed to occupy minimal PCB area.
Use the adapter plate on the ESP-07 and ESP-12 for easy use on breakout board or vero board.