What is the difference between types and interfaces in TypeScript?

In TypeScript, both type and interface are used to describe types, but there are differences:

• interface is intended for describing object structures and supports declaration merging. This is convenient for extending types across different parts of the code.
• type is more versatile: it allows creating aliases for primitives, unions, intersections, and other types, not just objects.

Example:

interface IUser {
  name: string;
  age: number;
}

type ID = string | number;

type UserWithID = IUser & { id: ID };

If you need to describe complex types with unions or intersections, it's better to use type. For describing objects and enabling extension — interface. In recent versions of TypeScript, the boundaries between them have become less strict, and the choice often depends on the style and requirements of the project.