Answer:
Rendering is the process made by the CPU, GPU or both to generate an image from a 2D or 3D model.
Step-by-step explanation:
The models to be rendered are mathematical expressions which the computer processes and calculates to obtain the "image" to draw on the screen.
Particularly in gaming, the screen image needs to be refreshed continuously since the obvious dynamic nature of games, so rendering is a process and memory demanding action for a computer. The more detailed, complex and quantity of simultaneous renders to be performed, usually requires dedicated hardware.