Imagine two lenses, both set to an aperture of f/2.8, filming the same subject with Christmas lights in the background. Lens A renders those lights as harsh, polygonal shapes with double edges. Lens B renders them as soft, round, "creamy" discs that melt into the background. Lens A has bad bokeh; Lens B has good bokeh.
This is the low-hanging fruit. The wider the aperture (the smaller the f-number), the shallower the depth of field. bokeh effect in video
In the lexicon of visual storytelling, few terms evoke as much immediate allure as "bokeh." It is the aesthetic quality of the blur produced in the out-of-focus parts of an image. It is the creamy background behind a tearful actor, the dancing circles of light in a night cityscape, and the visual tool that separates a professional cinematic look from a flat, amateur video. Imagine two lenses, both set to an aperture of f/2