A presentation aid may provide only audio assistance (such as a recording of a Harley-Davidson motorcycle engine), only visual assistance (such as a photograph of a person on a surfboard), or both audio and visual assistance simultaneously (as in a digital video recording of an exotic bird singing). Traditional aids include the speaker, assistants, objects, visual images (maps, photographs and drawings, diagrams), graphs (line, bar, pie), text-based visuals, and audio and video. Here, we take a closer look at each type of presentation aid.