Analysis of an image to determine setup and techniques that could be used to achieve certain properties of the image.
Reverse engineering is the process of discovering technological principles through analysis of their application. In context of this site, it occurs as analysis of images to determine likely camera settings, lighting and post-processing techniques that were used to create a certain look.
If you are interested in figuring out how a certain photograph was made, please read PSA on "What's this effect?" questions in order to make your question most effective and get the best answers.