Unreal Engine 4 defines a new method for creating materials. This method is based on the physical aspects of the real world. Things such as light reflections or heaviness will directly affect your model in the game world as visual elements and interactive behavior. You can make an ice cube that moves on the surface like a real one, or you can make waves of the ocean that have their own movements and reflect sunlight.
Basically, the quality of material has a direct connection to the graphics card and technologies involved in the CPU and the memory speed of the machine of a user. This leads developers and art directors to answer some important questions: how does our game render materials? Is it necessary that a user should have a super good machine to get what designers plan to show, or can we solve the quality aspect in simple ways?