The Rule of Thirds is a guidline in photography in which you align the objects of your photo in a certain way. You can use an imaginary graph made up of nine equal boxes to place your objects a third of the way into the frame from the left, right, top or bottom.
We use this rule because it makes for much more interesting photographs. Rather than lining things up in the middle or other awkward spot in the frame, putting it a third of the way in makes it much more appealing to the eye. My picture shows the rule of thirds because my subjects are lined up with the imaginary graph. The clock is a third of the way in from the right and the two benches in the background are a third of the way in from the left.