More often than I imagined I would have to look at this wikipedia definition of illustration... mainly for what it relates to not taking things too literally. I know this is not so obvious!
- give faces to characters in a story;
- display examples of an item described in an academic textbook (e.g. a typology);
- visualize step-wise sets of instructions in a technical manual;
- communicate subtle thematic tone in a narrative;
- link brands to the ideas of human expression, individuality and creativity; and
- inspire the viewer to feel emotion to expand on the linguistic aspects of the narrative.