Interfaces

Summary

A way to define the shape of an object — its properties and their types — so TypeScript can check that objects conform to a contract.

• 1Define an interface for a data model in one of your projects (e.g. `User`).
• 2Practice optional (`?`) and readonly properties on an interface.
• 3Learn when to use `interface` vs `type` — largely interchangeable, with a few differences.