This is Episode 16 of The Vibe Coder’s Guide to the Machine: computer science for a new generation.
Say you ask an assistant for one small piece of a shop: the function that runs when a customer places an order. A function is a named piece of code that does one job whenever another part of the program asks it to. You describe the job in a sentence: when an order is placed, send a receipt and reduce the stock. The assistant writes it, runs it on a sample order, and both things happen. Your sentence has become two lines inside the function, one for each thing, in the order you said them. Each line hands the work to a step, a separate piece of code with a single job, and the order function is the part that sets the steps going.
How those two lines are wired looks like a detail, and an assistant will settle it without asking. There are two ways for one part of a program to set another going. It can call the other part, or it can announce what happened and let whoever cares respond. Announcing frees the sender from knowing who listens, and the price is that the sender does not hear what happened next. Two orders, 1001 and 1002, show the difference, and the second one goes wrong.
