There are certain guidelines in photography about composition - but they're just that.  Guidelines.

The Rule of Thirds guideline tries to correct one of the most common mistakes in photography.  For some reason, when we take a picture, we subconsciously try to achieve symmetry.  We'll try to achieve it in every picture - unless we can break the habit.  Symmetry, while it can be very appealing in some pictures "usually" is a poor choice.  The Rule of Thirds tries to get you to think about breaking the symmetry habit.

Here's how it works:

Imagine that you split your viewfinder in thirds - both vertically and horizontally.  When taking a picture, try to put your subject at the intersection of two of these lines.  In the following diagram, you'd want to put your subject at one of the small circles - at one of the intersecting points of the horizontal and vertical lines.

If you photograph a person, you have a choice.  Take their whole body, the upper part of their body or just their head and shoulders.  Here's a question for you: In all of these scenarios, what is the "subject"?  You certainly can't put the whole person at one of these points!  I hope you answered "their head".  The person's head is often the subject (not always though - you might want their "hands" to be the subject or some other part of them).  The rule of thirds suggests that you should put their head at one of the four points where the lines intersect.  But which one??  Well, that's up to you, BUT, it's almost always best to have the person looking "into" the picture.  If their head is turned, even slightly, to the left, then put their head at the top-right intersection.  If their head is turned to the right, then put their head at the top-left intersection. That way they are looking "into" the picture.  Same rule holds true for animals.

If you photograph an inanimate subject, try placing it at one of these lines.  Buildings can be placed on either of the vertical lines while horizon lines are typically placed on one of the horizontal lines.

If you photograph a landscape picture, try to place the horizon line at one of those horizontal lines.  A picture with more sky than land or more land than sky is almost always more pleasing than one with equal amounts of land and sky!  Which composition do you like best?

In most cases, you can improve your pictures almost instantly by incorporating the rule of thirds.  All you have to do is remember it before you press the shutter button!!

Here's are a few simple rules that will help you put the Rule of Thirds to work: