composition - What is the "Rule of Thirds"?

Please can someone explain the "Rule of Thirds"?

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  What is it?

  
  


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  What does it tell me?

  
  



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  Why is it important?

  
  


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  What can I do with it?

  
  

Answer

The rule of thirds is actually the golden ratio. It's a number that divides a line into roughly 2/3 and 1/3.

In photography it's used to make images more dynamic. If you place the subject in the center of the image, it's percieved as balanced and perhaps dull (unless the subject is very strong in itself), while if you place the subject at one side you add a tension between the subject and the empty space:

<--------2/3---------><-----1/3----->

This can be applied both horizontally and vertically, and used for different purposes. The lower right spot is considered positive while the upper left is considered negative, which can be used to enhance what you want to express with the picture.

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Edit:

Updated link to an example of upper left positioning: http://www.guffa.com/Photo_view.aspx?id=5016