The Rule of Thirds is the first rule of composition. The basis of the rule is the frame being divded into horizontal and verticals thirds. By doing this four intersection points and four guiding lines. These can be used for horizons and vertical structures. Our eyes naturally rest of the intersections so putting key elements on these lines or points makes visual balance and interest. Forty-one percents of people seyes stop at the top left intersection, twenty-five percent stop at the bottom left intersection, twenty percent at the top right intersection and only fifteen percent stop at the bottom right point of intersection. Using this information you should try to put critical information in one of the first three corners and avoid the last one.
This image demonstrates the rule of thirds, showing the grid with the intersection points.
These pictures all follow the rul of thirds with key information being on one or two of the intersections.
This photo is my favorite photo that I took in the Rule of Thirds section. It demonstratrs the rule well with the key information of his head being on the top left intersection, the top of the tent along the top third line and the pole on the right third line.