In real-time rendering, 3D elements are rendered so quickly that they appear to be generated in absolute real-time. This method is mostly used in video games, VR, or interactive graphics, as it allows players to interact with the graphics instantly. The downside is that it's more difficult to achieve a high degree of realism as it's not fully based on physics; instead, several shortcuts must be taken to achieve such speed (although this is quickly changing as GPUs get more powerful over time).