The number of Flight Controllers (FC) for First Person View (FPV) drones can be overwhelming for beginners. This guide explains all the features and differences, and highlights important factors to consider when choosing a mini quad FC.
What is a Quadcopter Flight Controller
The flight controller (a.k.a FC) is the brain of the aircraft. It’s a circuit board with a range of sensors that detect movement of the drone, as well as user commands. Using this data, it then controls the speed of the motors to make the craft move as instructed.
Nearly all flight controllers have basic sensors such as Gyro (Gyroscopes) and Acc (Accelerometer). Some FC include more advanced sensors such as Barometer (barometric pressure sensors) and magnetometer (compass).
The FC is also a hub for other peripherals, such as GPS, LED, Sonar sensor etc.
FPV drone flight controllers are rapidly evolving: becoming smaller, with more features integrated, and using better processors and hardware.

This is a great article and will give you the fundamentals of flight controllers.
Read Oscar Liang’s full article here.