Everything can be rendered. You can render a graphic image, render lard, and render results. Rendering is also used in film-making, but most importantly it's also a substance that's applied to brick, concrete, stone, earth or cement surfaces - often to hide imperfections and add aesthetic appeal.
You'll mostly find rendering done outside but interior walls can also be rendered for textural effects, and render can be applied to columns, postboxes, walls and fences.
What kinds of render are there?