Representational State Transfer — an architectural style for designing networked APIs. RESTful APIs use HTTP methods to perform CRUD operations on resources identified by URLs. Responses are typically JSON.

JavaScript Object Notation — a lightweight text format for data exchange. JSON supports strings, numbers, booleans, null, objects, and arrays. It's the standard format for API responses and configuration files.

The modern browser API for making HTTP requests. fetch() returns a Promise that resolves to the Response object. It replaces the older XMLHttpRequest (XHR) and works with async/await.