Wat zijn union en literal types?

// Union type
type Status = string | number;
const status: Status = "active"; // OK
const code: Status = 200;        // OK

// Literal type
type UserStatus = 'active' | 'inactive' | 'pending';
const userStatus: UserStatus = 'active'; // OK
// const userStatus: UserStatus = 'deleted'; // Error!

// Discriminated union
type Response = 
  | { status: 'success'; data: any }
  | { status: 'error'; message: string };

const response: Response = {
  status: 'success',
  data: { name: 'Jan' }
};