Rule of Thirds
This guideline states that an image is divided into nine equal parts by two horizontal lines and two vertical lines, and the key elements are placed along these lines or their intersections.
The Rule of Thirds works because it demands that the artist makes one element more dominant than another. This dominance creates an imbalance, and an imbalance of any sort will always attract the viewer's eye.
Bisecting an image perfectly in half creates the least amount of interest, because everything is equally balanced.Making one area of your composition more dominant creates tension, and therefore adds interest. It also makes your eyes move around the canvas more to compare all of these relationships.