Here's a preview of what is esp8266 esp-12 wifi module and what it's capabilities.
What is esp8266?
ESP8266 is a highly integrated chip designed for the needs of a new connected world. It offers a complete and self-contained Wi-Fi networking solution, allowing it to either host the application or to offload all Wi-Fi 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.
you can clearly see the pin numbers of esp8266 esp12 wifi module
This particular which comes with the pre-loaded firmwire from ai thinker which you can directly interface with the app provided by the ai-thinker , you can also downloaded the app from this link click here
Note: Make sure you remove the jumper pins in order to use with the app, the jumper pin should be in that place only when we upload a new firmware to the esp8266 wifi module.