In some technical documents, it is essential to have visuals, whether those be photographs, charts, tables, line drawings, screenshots, or other elements. And while, as writers and editors, we usually pay attention to the quality of those visual elements, all too often the caption work that goes with them suffers. For many technical documents, the captioning is just as essential a writing task as the larger piece that houses the visual.
In particular, I want to discuss the use of visual elements in documents. The recommendations that I make here will not carry over, necessarily, to user manuals, training pieces, or presentations. Those genres of technical writing have their own media-driven needs regarding visuals.