What: Dividing the frame into nine with two horizontal and two vertical lines, placing the subject at an intersection.
Why: A subject in the dead centre is static; on a third-point it gives balance and energy.
How: Imagine the grid, place the key element on an intersection, and leave space in its gaze or motion direction.
Common mistake: Always centring everything, so the image loses its dynamism.
Exercise: Shoot a scene twice: subject centred then on a third-point, and compare.