What is the rule of thirds? Well, it's not really a "rule" but more a "rule of thumb" or guideline, the Rule of Thirds applies to the process of composing visual images that are considered optimally appealing to the eye of the viewer.
The guideline proposes that an image should be divided visually (either through the view finder or during post processing) into nine equal parts. The division in separated by two equally-spaced horizontal lines and two equally-spaced vertical lines. It's thought that the important compositional elements of the image should be placed along these lines or where they intersect.
It breaks down to an image split into thirds. These thirds are both vertical and horizontal. The idea is to put the subject of your photo 1/3 from any edge of the frame, and to line, say, a horizon 1/3 from the edge of the frame, too. Below is and example of the Rule of Thirds.
|This photograph of a sunset taken in the Thousand Islands|
region demonstrates the principles of the rule of thirds
As you can see, the horizon is on the bottom third of the photo. And the subject (tree) sits in the "crosshairs" of the bottom right thirds (Where the horizontal and vertical lines intersect at the bottom right of the photo).
Now...go out and rule the rule of thirds!