Incomplete documentation of "Freshness" and "Structural typing" on https://basarat.gitbook.io/typescript/type-system/freshness

It is never defined or explained, what actually "Freshness" and "Structural Typing" are.

> TypeScript provides a concept of Freshness (also called strict object literal checking) to make it easier to type check object literals that would otherwise be structurally type compatible.

> Structural typing is extremely convenient. Consider the following piece of code. This allows you to very conveniently upgrade your JavaScript to TypeScript while still preserving a level of type safety:

But, what is the concept of Freshness? What does it mean to be _structurally compatible_ and what is _structural typing_?

The correct explanation is

```
function logName(x: { name: string }) {
console.log(x.name);
}

const person = { name: "Alice", age: 30 };
logName(person); // ✅ OK — structurally compatible.
logName({ name: "Bob", age: 30 }); // ❌ Error -- Freshness; passed a fresh object

```

Freshness means no extra properties are allowed if an object literal is passed straight away.

Structurally compatible means if the object is first stored in a var, it _can_ be passed with extra properties.

Open the Freshness page at https://basarat.gitbook.io/typescript/type-system/freshness and review the existing explanations alongside the issue's examples. Done means the page defines Freshness and structural typing, explains structural compatibility, and makes clear why the direct object literal differs from the stored variable.

Written by the indexing model from the issue text.