I came across a post on DPreview by Mark Schretlen regarding the importance of using a hood on your lens. I asked him to contribute here for others to benefit from his example. He not only did that but also provided a link on my lenses page that shows real world examples using different lenses. Thank you Mark.
As photographers we are often willing to spend more for a particular lens when we know it has better color, contrast, and flare control than a competing brand. A simple and inexpensive way to get the most from your lenses is to make a habit of always using a lens hood. The example demonstrates how color, contrast, and flare reduction are improved with a lens shade when a single light source (the sun) is on the fringe of the viewfinder. When shooting where multiple light sources are present (indoors) it becomes even more important to use a lens hood.