The rule of thirds is one of the main compositional rules in visual arts, including painting, design, and (of course) photography. This rule is based around the idea that an image should be imagined as being divided into nine equal parts by two equally spaced horizontal lines and two similar vertical lines, as shown in the photograph below. The rule continues on to state the important elements within the photograph, on these lines in order to obtain a successful photograph.Photographers claim that the reason use this technique is because it creates tension, energy and interest in the composition, more so then a photograph where the subject is dead center. For example, in the photograph below, the main subject is centered on one of the vertical lines, with the subjects eyes centered on one of the horizontal lines.
However, points of interest in a photograph do not necessarily have to lie on these lines to take advantage of the rule of thirds. If a point of interest lies on the intersection between two lines, this also is considered to be using the rule of thirds. This intersection of two lines is often called a power point, and it is common to see a photograph place a subject of aspect of what they are photographing at this point.
As mentioned earlier, the rule of third is not a technique used solely in photography. In any art form that has a main subject or point of interest, the rule of thirds is often used. In addition to photography, film uses this compositional rule as well. If filming a moving subject, the same pattern is followed with the majority of the empty space in front of the subject or in the direction that they are moving towards.
The rule of thirds was first used as early as 1797 as a rule for creating correct proportion in scenic paintings. In J T Smith's illustrated book, published in 1797, the rule of thirds is clearly defined. "...the rule of thirds according to which a landscape having one third of land should have two thirds of water, and these together, forming about one third of the picture..."
Any person who is avidly involved in art or photography would agree that using the rule of thirds is a good idea to make your photograph much more interesting and professional. Often, digital cameras will have a setting that allows the photographer to permanently have a set of lines following the rule of thirds in their viewfinder. However, it is also easy to do manually by eye and guessing. Like with most forms of art, this rule does not need to be perfect.