The main goal of high-end visualization is to create the photorealistic image, as close to reality as possible. Modern softwares use a lot of different technics from ray casting and ray tracing to rendering equation, which simulate how the objects are lightened in the real-world. That's why our brain could be fooled easily, and in many cases it's hard to distinguish, where ends the world that surrounds us and begins the 3D virtual world.
We can say that 3D rendering is quite similar to photography in so many aspects. For example, a rendering software, will it be Corona Renderer or V-Ray, or anything else, points a camera towards an object to compose a photo. It also adds super realistic lights and shadows. Though, all the latter process of recreating reality depends on the visualizer. In this job everything is important.
Nowadays a bunch of different rendering techniques are being used. Still, there is something similar in all of them: the main thing about any great visualization is to capture an image based on how light hits the separate objects, just like it does in the reality. If we can't see the difference between the photographed the 3D that means the render is done in its best way.