A caption is the voice of an image. It speaks for a photo; a diagram; a chart; a bar graph; a drawing; an outline; a list.
It is the job of the writer to give the image voice so that the reader understands its significance and value.
After you have given the caption a title, what other details should be included? You might consider the WALTER approach to writing a clear and helpful caption. Remember — the caption should serve to advance your ideas and bring your reader to a better understanding of your point of view.
Jelena Marašević, a PhD student in the Department of Electrical Engineering at Columbia University, attended my Academic Writing class for PhD students this September-October. Here is what Jelena says about captions — and here are her before and after captions for the same image. Thank you Jelena!
“Before taking the class, I was not sure what to write in a figure caption. I thought that it is better to only have a title for a figure, and explain in the text what the figure presents. Here is an example of the same figure I used in a project report in the Spring semester, and that I am using in a paper I am currently writing (the relation before-after should be clear).”