How software works (mental models)

Module 1 is four short picture-lessons on the shape of any web product: how the browser talks to the server, where the information is kept, who is allowed to do what, and how an app goes public. Each has its own everyday scene: a restaurant, a filing cabinet, door staff with a guest list, and an opening night.

This module is reference you can read at any time. If you arrived from Module 0 with a first page already built, you don't have to read it before Module 2: each Module 4 build lesson names the lesson here whose picture it uses, and on the course site this module never locks anything. Read it in full whenever you want the whole shape at once.

What this module builds

By the end of this module, you can sketch — in plain language, on paper — the durable shape of any web product: where each piece sits, how the pieces ask each other for things, who's allowed to do what, and how the whole thing reaches the public.

Each lesson builds on the last:

• Lesson 1 — How the web works: you can trace what travels between a browser and a server when a page loads → sets up Lesson 2 by leaving one question open — once the server gets the order, where does the answer actually come from?
• Lesson 2 — Where data lives: you can place any piece of a feature in one of three rooms — screen, server, or the cabinet where the data is filed — and show how a question and answer pass between them → sets up Lesson 3 by raising the next question — anyone could walk up and ask, so who's actually allowed to?
• Lesson 3 — Who can do what: you can separate "are you who you say you are?" from "are you allowed to do this?", and say what the hand stamp does once the door waves you through → sets up Lesson 4 by leaving the app still locked inside one private building.
• Lesson 4 — How it goes live: you can trace the path from an app on your own computer to a public address anyone on the internet can reach → sets up Module 2, where you meet your agent properly and the saving habit that keeps the recipe binder current.

The thread that ties it together: one picture grows across all four lessons. A restaurant (a browser ordering from a kitchen) gains a filing cabinet in the back (where the data is kept), then door staff and a guest list at the entrance (who gets in and what they can touch), and finally an opening night that turns the private kitchen into a public restaurant via a recipe binder anyone's prep cooks can read.