# What are runes?

> [!NOTE] **rune** /ruːn/ _noun_
>
> A letter or mark used as a mystical or magic symbol.

Runes are symbols that you use in `.svelte` and `.svelte.js`/`.svelte.ts` files to control the Svelte compiler. If you think of Svelte as a language, runes are part of the syntax — they are _keywords_.

Runes have a `$` prefix and look like functions:

```js
let message = $state('hello');
```

They differ from normal JavaScript functions in important ways, however:

- You don't need to import them — they are part of the language
- They're not values — you can't assign them to a variable or pass them as arguments to a function
- Just like JavaScript keywords, they are only valid in certain positions (the compiler will help you if you put them in the wrong place)

> [!LEGACY]
> Runes didn't exist prior to Svelte 5.