The ESP8266 Wifi module is one of those new and upcoming wifi modules. The thing that makes this module so popular is the price and the ability to update the firmware. There is a V2 of this PCB coming out which will allow you to update firmware with a simple switch and reset. This PCB like many of my others allows you to save so much space wire your wifi module with ease. The module also hangs off the edge (if placed there) so its further away from any interference as well. Comes with a nice Arrow to tell you which way the module should face.