Dictionary.com defines Bokeh as - A Japanese term for the subjective aesthetic quality of out-of-focus areas of a photographic image. No matter how one defines it, the blurred background of most photos adds a pleasant look to the picture and leads one's attention to concentrate on the subject at hand.
|Green Bee-eater in Bandhavgarh National Park, India|
DigitalRev put out the video below to illustrate how to take photos with varying bokeh. Generally, a longer lens gives more bokeh than a shorter lens with the same aperture setting. You can see more examples of different bokeh on my website - MichaelDanielHo.com