Active zones

Create a grid of 2 equally spaced vertical and 2 equally spaced horizontal lines — dividing a rectangle into 9 equal parts — and you’ll have an example of the rule of thirds.^[1] According to this rule, people tend to concentrate their attention along these lines and particularly at their intersections — the active zones of a composition. 

Photographers are taught the rule of thirds early on in their studies, as it’s one of the easiest ways to create a visually appealing, balanced composition. Designers should pay careful attention to these intersections when placing important page elements.