You have wired a torch in your head before — a cell, a small bulb, a switch, some wire. Now imagine you had to tell a friend in another village exactly how to build it, using only a piece of paper. You cannot post the torch to them. You can only draw.
If you draw a realistic picture — a fat battery, a curly wire, a little glowing bulb — your friend will spend an hour just guessing what each squiggle is. So instead, every electrician, every physicist, every textbook in the world agrees to use the same small set of signs. A short line means this. A little circle means that. Once you know the signs, you can read any circuit and draw any circuit.
That shared set of signs is what this topic is about.
1. The Problem: a photo is not a plan
Here is a real torch circuit, drawn as a picture:
A round cell with a bump on top, two bendy copper wires, a press-button switch, and a tiny bulb in a holder. Someone has shaded the cell grey and drawn the bulb glowing.
Now ask yourself one thing.
Stop scrolling. Try it in your head before reading on. Which end of that cell is positive? In the photo, you genuinely cannot tell. The bump might be +, or the artist might have just drawn a bump. The wires cross near the switch — do they touch there, or pass over each other? A photo hides the very things you need to connect a circuit correctly.
This is the trouble with realistic pictures. They show how a thing looks, not how it is joined. For electricity, joining is everything.
So we move to a circuit diagram — a drawing that throws away looks and keeps only the joins. Every component becomes a fixed symbol. Every wire becomes a straight line. Nothing is shaded, nothing is pretty. And because it is plain, it is exact.
You can now say why a photo is a poor way to record a circuit.