Background

What is behind your center of interest is often as important as the center of interest itself. A cluttered background is often distracting, and takes away from the focus. A simple fix is to make the background go out of focus by decreasing the depth of field. The depth of field is determined by the aperture opening. A larger aperture creates a smaller depth of field.

The background here is rather distracting.

The out-of focus background allows for the center of interest to be the focus.