The origin of word Bokeh came out from the Japanese word boke which means “blur” or “haze”. The other word from where it is derived is boke-aji which means “blur quality”. Bokeh which is widely used in photography and cinematography is defined as “the effect of a soft out-of-focus background that you get when shooting a subject, using a fast lens, at the widest aperture, such as f/2.8 or wider.”
The lens used while capturing a photograph decides the shape and size of visible bokeh. Rounder and softer out-of-focus highlights are produced by a lens with circular shaped blades. A lens with hexagonal shaped blades will reflect that particular shape in highlights.
One has to use a fast lens to achieve bokeh in an image. A lens with an aperture of at least f/2.8 aperture works. Fast prime lenses are used by many photographers these days to produce bokeh.