Artwork that contains organized information for easy reading, identification, and comparison. On Danbooru this usually takes the form of a tabular set of panels (e.g. expression chart), or a lineup of subjects to be compared visually (e.g. height chart)
Not to be confused with diagram, which points out or explains the details of something instead of comparing multiple things, or with graph, which is for visualizations of numeric data (e.g. bar charts, pie charts, etc).