This is referred to as leading the subject. Rule of Thirds E xcept, possibly, for closeups of people, it is often best to place the center of interest near one of the points indicated by the rule of thirds . In the rule of thirds the total image area is divided vertically and horizontally into three equal sections. Although it is often best to place the center of interest somewhere along the two horizontal and two vertical lines, generally, composition is even stronger if the center of interest falls near one of the four cross-points. Note that the photo on the left has a center of interest that is consistent with the rule of thirds illustrated above.
Some cameras even have the rule of thirds gridlines visible in their viewfinders.
Here are two more examples. But, remember, we are speaking of a rule of thirds, not law of thirds. Note that the composition in the scene above does not follow the rule of thirds. Horizontal and Vertical Lines W eekend snapshooters also typically go to some effort to make sure that horizon lines are perfectly centered in the middle of the frame. This also weakens composition by splitting the frame into two equal halves.