What is render made from?

I'm quite curious about the origin of render. Could you please elaborate on what render is actually made from? I've heard it's used in various fields, from computer graphics to film production, but I'm still hazy on its fundamental components. Is it a physical material, or is it more of a digital construct? If it's digital, how is it generated and manipulated? And if it has physical properties, what are they and how do they contribute to its overall functionality? I'm really interested in understanding the ins and outs of this fascinating concept.