# Welcome — read this first

## Welcome to CA UK docs

This is where we document how the CA UK websites work, how the different JSON feeds talk to each other, and anything else worth writing down.

### How content is organised

BookStack uses a four-level hierarchy:

- **Shelves** — optional groupings that hold multiple books.
- **Books** — the main unit. One book per subject (e.g. "National website", "District shop").
- **Chapters** — optional sub-sections within a book.
- **Pages** — the actual content.

### Logging in

Click **Log In** at the top right. Public visitors can read content without logging in.

### Next steps

1. Read *Writing your first page* to learn the editor.
2. Read *Diagrams and images* to see how to draw architecture diagrams directly in a page.
3. Read *Organising content* to learn about books, chapters, and permissions.