Idea photo essays have some common theme that fits them together. These essays cover a broad range of ideas. As long as the photos all follow a common idea, the rest of the photo can be as diverse as you can imagine. As an example, let’s say you have a horse. You take photos of this horse at the beach, at the desert, in a forest, and in the mountains. This essay can still be documented together because they all prominently feature your horse.
An idea photo essay does not necessarily have to document a particular thing. It can also convey an emotion. You can take photos that you feel express doubt, sadness, love, fear, anger, or a range of other emotions. These photos also must flow together, but only to a point. They can be much less literal than other forms of photo essays. Take for example a photograph of a tree. In the far distance behind the tree is an office building, so your next photo could be of a window washer. Reflected in that window is a restaurant so your next photo can be of a chef. These photos all suggest the next photo in the series without being obvious or too literal.