Bokeh is "the way the lens renders out-of-focus points of light." It is a Japanese word meaning blur or haze. It has become a popular creative tool of late.
There are some who interpret bokeh as any out-of-focus region in a photograph. This, to me, would take out the creative/artistic aspect of it, because simply, most out-of-focus regions are boring. As an example, the background in this picture is not focused, but it also adds nothing (creatively) to the photograph:
The next example gets a bit closer to what I would consider "good" bokeh. Using a macro lens to get close to the fake rose petals rendered the Christmas tree lights as slightly indistinct circles, rather than points of light:
Still, in my opinion the bokeh could be better. In the next picture, I focused on the drops of rain on the window pane, which made the street- and headlights from the world outside go all bokeh on me:
Some people actually use special lenses to get particular shapes with their bokeh, like heart or star shapes, for example. I will never go that far. But, I do concur that bokeh is more interesting when it's not just the same old blurred-out lights again and again. In the final example, the bokeh created behind the butterfly is made up of random patterns caused by the leafy background. I think it rocks:
I suppose it's alright for a photographer to use bokeh to describe any out-of-focus region; I just feel that bokeh is something that is meant to stand out, to create interest.
Here are a few more sa-weeeet images created by photographers who have definitely put in the effort:
(photos courtesy of www.lemonsandcoal.com, www.lullaby.homepage.dk, www.digital-photography-school.com)