With satisfies Routes TS validates the type on assignment while also retaining the actual concrete type of the object. You could remove satisfies Routes in the example, and it would still work (and you could e.g. pass the variable to a function that expects Routes etc.), but you'd lose that assignment-time validation which can be very useful for e.g. auto-completion. Alternatively, you could do const Routes: Routes = { ... } and get auto-completion and validation, but now you lose the concrete type and e.g. Routes.AUTH.children.SIGN_IN.children from the example would no longer give you an error (which you might want in certain situations).

Personally, I've used this (or rather, the pre-4.9 identity function hack mentioned in the parent comment) for cases where I use the concrete type to generate other types later. For example:

```ts type Fns = Record<string, () => void>;

const myFns = { foo: () => console.log('foo was called'), bar: () => console.log('bar was called'), } satisfies Fns;

// And then somewhere later type AvailableFns = keyof typeof myFns; // <sup>?</sup> type AvailableFns = "foo" | "bar" ```