What is the left-hand thumb rule?

Based on Fleming’s left-hand rule, the left-hand thumb, index finger, and the middle finger is stretched and kept perpendicular to each other. If the index finger is in the direction of the magnetic field, and the middle finger points in the direction of the current, then the direction of the thumb is the direction of the force on the conductor. That is, if the direction of the electric current and the direction of the magnetic field are identified and then the direction of the force exerted is perpendicular to both.