Composition: Rule of Thirds

It's always nice to start with a definition, so I found one from an on-line dictionary:
composition
n.

1.

a. The combining of distinct parts or elements to form a whole.

b. The manner in which such parts are combined or related.

c. General makeup.

d. The result or product of composing; a mixture or compound.

2. Arrangement of artistic parts so as to form a unified whole.

3.

a. The art or act of composing a musical or literary work.

b. A work of music, literature, or art, or its structure or organization.

So really for this blog I am looking at 2 - "Arrangement of artistic parts so as to form a unified whole" and hopefully one where the whole is greater than the sum of the parts.

The "Rule of Thirds" is one tool that can assist with arranging compositional elements of an image to develop balance.  This is not about equal weighting to each side of an image but rather a balance that can help an image appear pleasing to the eye.  It goes back before photography, with many examples being found in art for many centuaries.

Thirds, unsurprisingly, comes from dividing the image into three.  This is done both horizontally and virtically to develop a grid pattern.  Now for the rule. Use the lines and intersecions to place your subject or points of interest. 

With landscapes aim to place the horizon on one of the horizonal third lines dependant upon whether the sky or land is the main subject.

Aim to place specific elements/objects at the intersections, helping the balance of the image.  This will aid anyone looking at the image as their view moves around the picture.

However, rules are made to be broken.  As a general guide the rule of thirds is really useful and is a great aid to composition.  It will depend upon what you are tyring to achieve with the image - sometimes it just works to put the subject in the middle of the image, or anywhere else for that matter.  So more of a guide than a rule.