probably almost everybody tinkering with electronics has heard of the wonderful ESP8266 MCU with embedded wifi. It is a really cheap, yet very powerful wifi module with an Arduino like hardware interface (GPIO, SPI, ADC ...). Usually it doesn't ship as a chip but as module. There are plenty of different modules and we focus here now on the ESP8266EX-12
On the right you see the PCB antenna and a LED (once I have more time I turn the image). The chip and its external Flash is hidden by the metallic cover. This combination received the FC certification with the comment that you should always stay at a distance of at least 20cm to avoid negative impact to your health.
There are plenty of different firmwares in development, for me currently the most reasonable usage today is using the NodeMcu Lua based environment.
* Plug in CH_PD after starting flashing
* Remove GPIO0 for user/serial access mode
* type commands sometimes twice