The rule of thirds is a concept in which the screen is divide into nine imaginary sections as shown in image below. By dividing the screen into 9 equal sections we get reference point which guides us in framing the image.
Subject or a point of interest should be placed at 1/3rd or 2/3rd across the frame rather than placing in the centre of the screen. It balances your image without making it appear too static.
Limitations of Rule of Thirds.
What if there is nothing in the image to apply the rule ? This usually happens in extremely abstract compositions. In this case you should still apply the rule to strike balance in the image. Look for brighter or darker spots to compose your image. This will effectively create an off centre composition.
Breaking Rule of thirds
Most artists or photographer feel cramped due to rigidity of the rule. But rules are meant to be broken and this one’s no exception. You can place the subject in the center if you want to show the symmetry of the subject.