TypeScript Error: Type 'string | undefined' is not assignable to type 'string' — how to fix?

Hi! I'm new to TypeScript and encountered a confusing error. I have an interface for a user where the `name` field is optional (can be `undefined`). I'm trying to get this name and pass it to a function that only accepts a string, but TypeScript complains. Here's my code: ```typescript interface User { id: number; name?: string; // optional field } function greet(name: string) { console.log(`Hello, ${name}!`); } const user: User = { id: 1, name: 'Anna' }; greet(user.name); // Error: Type 'string | undefined' is not assignable to type 'string' ``` I thought that if the `name` field exists, it's definitely a string. But the compiler says it's `string | undefined`. Why does this happen and how do I properly handle this situation? I tried just ignoring the error with `// @ts-ignore`, but that's bad practice. Please advise how to do it correctly so the code is type-safe? Maybe there are several ways to solve it? Thanks in advance for your help!