The general term “figures” encompasses all the graphics that are not tables. Whether or not one may be prepared to call them art, these visual aids can be vitally important in presenting a scientist’s message. They summarize and emphasize key points and reduce narrative length. They simplify information and in this way enhance understanding. They improve the conciseness and clarity of the narrative. And finally, when carefully crafted, they add visual appeal.

Use figures when one will make your point more successfully than the text or a table would. Generally figures are necessary for one of three E’s: evidence, efficiency, or emphasis. Evidence is easy. If something of visual interest occurs during a clinical trial or a case study, one naturally wants to document it with a photograph. During a taxonomic study, an unusual structure or notable range in a character’s expression seems to beg for illustration.

Efficiency implies that the figure is the most succinct and effective way to make a particular point. In a scientific paper, for maximal efficiency one should generally combine material rather than presenting a repetitious series of similar figures. Draw several curves on a single graph. Combine diagrams to illustrate steps in a procedure, or cluster photographs to show morphological variation in a trait. Illustrations prepared for oral presentations generally present a relatively limited amount of information; they usually can and should be combined for publication.

Emphasis, the third E, is a major reason for using illustrations in a spoken talk, and often in popular science writing. However, journal editors may consider emphasis alone to be insufficient for a published research paper. Most editors will stringently assess each figure’s usefulness in communicating the message of the paper.