In real-time rendering, most common in video games or interactive graphics, the 3D images are calculated at a very high speed so that it looks like the scenes,
which consist of multitudes of images, occur in real time when players interact with your game.

That’s why interactivity and speed play important roles in the real-time rendering process. For example, if you want to move a character in your scene,
you need to make sure that the character’s movement is updated before drawing the next frame, so that it’s displayed at the speed with which the human eye can perceive as natural movement.

The main goal is to achieve the highest possible degree of photorealism at an acceptable minimum rendering speed which is usually 24 frames/sec.
That’s the minimum a human eye needs in order to create the illusion of movement.

Even though rendering is based on tons of sophisticated calculations, modern softwares can offer some fairly easy parameters for you to understand and work with.
A rendering engine is usually included in a modern 3D game engine and it can achieve really amazing graphics.