the earth is art,
definition of rule of thirds
The rule of thirds is applied by aligning a subject with the guide lines and their intersection points, placing the horizon on the top or bottom line, or allowing linear features in the image to flow from section to section.
Within my own words, rule of thirds is making sure that the focal point of a picture isn't in the center of a frame. The focal point of the picture should belong within any of the other boxes other than the center.