The rule of thirds

The rule of thirds:The rule of thirds is a "rule of thumb" or guideline which applies to the process of composing visual images such aspaintings, photographs and designs.^[1] The guideline proposes that an image should be imagined as divided into nine equal parts by two equally-spaced horizontal lines and two equally-spaced vertical lines, and that important compositional elements should be placed along these lines or their intersections.^[2] Proponents of the technique claim that aligning a subject with these points creates more tension, energy and interest in the composition than simply centering the subject would.

This picture is perfect!

Y this photo no follow the rule of thirds 

Disclaimer:  these pictures are not mine, I have borrowed them for educational purposes.