HDR (High Dynamic Range) is a process of taking three or more exposures of the same scene. Typically one makes one exposure to capture the brightest part of the scene, one for the darkest and another about halfway in between. Software designed for HDR will then merge these images using the best parts of each one to create one final image that has good exposure in all areas. This technique is great anywhere there’s a great contrast between dark and light. I think it works great in real estate photography where otherwise you’d need to choose between exposing the interior (and outside would be blown out) or expose for outside (and interior would be too dark) or setup lights & flashes.
One way to help automate this process is to setup your camera to use bracketing where with one press of the shutter it will take three images at -1 EV, 0 EV and +1 EV. Or, some later model cameras can be set to HDR mode where it will do the bracketing and combine them in-camera. For these images, I did it with all manual settings then merged and tonemapped in qtpfsgui, an HDR application for Linux. Darktable is another application that do this.
— Kenn Ranous