# §1 — You are about to build something

Nothing has been decided yet except the one thing that decides everything else: where it runs.

The language follows from it. So does the way you ship a fix on a Friday, the way a stranger installs it, and how much of what you write you will still recognise in a year.

Atlas is two boilerplates for two answers. Pick the one you are actually building, not the one that sounds more ambitious.

## Where now

- In a browser — or answering one — turn to §14 (An API, a site, a service. Bun and TypeScript.)
- On someone's machine, in its own window — turn to §31 (A native app. Rust, gpui, and guise.)
- Both, and they do not talk yet — turn to §22
- I know what I want — show me everything — /map/ (The full module chart.)