Flight Controls
When a drone pilot uses the controller to move the drone along the three axis of movement, it will tell 2 or more rotors to speed up or slow down in order to execute an instruction.
If Rotors all speed up: the multicopter ascends (produces more lift)
If Rotors all slow down: the multicopter descends (produces less lift)
If Rotors on the right speed up: will make the multicopter bank (move) to the left
If Rotors on the left speed up: will make the multicopter bank (move) to the right
Each Rotor in a pair: spins the opposite direction to counteract torque (turning forces)
Image Source: https://makezine.com/projects/the-handycopter-uav-2/