The rule of thirds suggests that an image should be composed as if divided into nine equal parts by two equally-spaced horizontal lines and two equally-spaced vertical lines with important elements of interest placed on or close to these lines or their points of intersection.
The rule of thirds grid on the left can be overlayed onto images to determine whether the rule of thirds is being satisfied. Below are also various examples that follow the rule of thirds.
To learn more about the history of the rule of thirds, and the theory behinds its effectiveness or to see more examples of its application, consult a search engine.
Golden Ratio (Golden Mean)
The like rule of thirds, the golden ratio suggests that an image should be composed as if divided into a series of geometrically similar rectangles with important elements of interest placed on or close to these lines formed by the rectangles or their points of intersection.
The golden ratio grid on the left can be overlayed onto images to determine whether the golden ratio is being satisfied. Below are also various examples that follow the golden ratio.
To learn more about the history of the golden ratio and the mathematics behinds its calculation or to see more examples of its application, consult a search engine.
The diagonal rule suggests that important elements of interest should be placed on or close to diagonal of the image.
Leading Lines Rule
A corollary of the diagonal rule, the leading lines rule suggests that the natural geometric elements such as the lines of an image should be composed to extend from the corners of the image in order to draw and lead the viewer's eyes through the image.
Framing Within the Frame
Framing within the frame suggests that an image may be enhanced by using natural elements such as doors, curtains, trees, etc to provide an additional border or enclosure.
Other Composition Rules
Composition rules are not limited to only those explained and demonstrated here. For information on more composition rules such as the rule of odds, rule of space, rule of symmetry and geometry, etc consult a search engine.
Keep in mind that composition rules serve merely as a guide to help you properly compose a photo. Once you become familiar with how to properly compose a photo either through studying these rules or through analyzing photos and seeing what compositions appeal to you, you can compose your photos without referencing these rules. Often you will find that your final compositions intuitively fall close to those dictated by these rules.