Good captions generally contain a subject and a verb. They are informative without being lengthy. Visuals should be appropriate for their task. Visuals exist in many formscharts, illustrations, graphs, maps, photographs, tableseach having its own unique communicative capabilities. The proper choice of visual depends upon what we are trying to achieve with the visual.
Charts depict relationships between two or more variables, possibly at distinct points in time.
They can also illustrate the flow and relationship of steps in a process, display organizational relationships, or identify the relationship of parts to a whole. Illustrations and diagrams show conceptual objects, providing perspectives on existing objects or assemblies that photographs cannot capture. They can show exploded views, focusing attention on smaller parts of a larger assembly. Graphs depict the relationship of two or more variables and show how those variables change. They also permit comparisons and show trends.