The flight controller has sensors to aid stability. It is programmed to make flying easier, with the Barometer ( for height Height), an accelerometer and provides connectivity for things like GPS. With the GPS attached, you loose sight of your machine, you can switch in RTH, it will then come back by itself. Connect the receiver either channel by channel, or one could program the system to serial and feed the receiver to a bus port, where you only need two wires. The FC connects to the esc's. You will have to research how to enable the serial connection. Dont fly without it, you will crash....lol