The Rule of Thirds

The rule of thirds is typically one of the hardest concepts to understand, in painting & drawing a similar concept is called the golden triangle..  That being said many cameras and phones automatically overlay a grid or have the ability to overlay a tic tac toe grid.  This is the basic idea behind the rule of thirds, and although there are infinite possibilities for the application of this concept the idea remains the same.  The way I've always thought of it is the visual break up of the image.  For instance a sunset picture might have the horizon line at the top third of the picture while the water meets the sand near the bottom third of the picture.  Aside from Horizontal or vertical the most important element in composition is using the rule of thirds.

I chose this example because of the light and dark areas of the photo.  The dark area on the right takes up about 1/3 of the entire space of the image while the lighted area takes up the other 2/3's.  This concept is not about mathematics so much as it's about visually distributing subject matter in a balanced and smooth fashion.  It's a concept that can be shown several different ways.