REST API
An interface that allows applications to communicate over HTTP using standard methods like GET, POST, PUT, and DELETE. WordPress has a built-in REST API.
A REST (Representational State Transfer) API is a set of rules for how applications communicate over HTTP. It uses standard HTTP methods: GET to retrieve data, POST to create, PUT to update, and DELETE to remove. Data is typically returned in JSON format.
WordPress includes a built-in REST API (available at /wp-json/) that exposes posts, pages, users, and custom content types to external applications. It is the foundation of headless WordPress setups and is used by the Gutenberg block editor internally.