Quote - Sorry, reading my comment back, I do sound flippant. Such was not my intent and I apologize. It's just that I thought a shader was something you used to give an object texture and the way Robynsveil used the term, it is more like a tutorial. The link she provided took me to a discussion way, way over my head. If I knew enough to follow that discussion I probably would never have had  to ask the question in the first place, that was where my remark about English came in. When I asked, I was looking for an answer like Basicwiz gave (step 1, Step 2...), not how it works in theory. Again, very, very sorry. I stand corrected and humiliated.

Please don't apologise, SB - no reason to: people take different approaches to learning. I learn best from pdfs and written material. Some prefer videos. And BasicWiz's method is indeed the best when you just want a quick dot-point approach (which I like as well, tbh).

Les did explain it well, better than I did. Sometimes pointing you to the Gray's Anatomy book when all you want to know is why your elbow aches isn't quite the right approach (and which can be easily construed as being flippant as well - analogous to RTFM, which i loathe).

Monterey/Mint21.x/Win10 - Blender3.x - PP11.3(cm) - Musescore3.6.2

Wir sind gewohnt, daß die Menschen verhöhnen was sie nicht verstehen
[it is clear that humans have contempt for that which they do not understand] 

Metaphor of Chooks