JSON:API 101: UNDERSTANDING JSON:API IN DRUPAL

The JSON:API module is a fully compliant implementation of the JSON:API Specification. In its own words, the JSON:API specification is:

A specification for how a client should request that resources be fetched or modified, and how a server should respond to those requests.

Drupal 8.7 ships with JSON:API which makes a solid and stable path to support decoupled Drupal through standardisation of payload structures and query string parameters.

JSON:API is designed to minimize both the number of requests and the amount of data transmitted between clients and servers. This efficiency is achieved without compromising readability, flexibility, or discoverability.

Drupal's data-structures, i.e. entity types, bundles, and fields, are incredibly well suited to the JSON:API.