Definition
JSON (JavaScript Object Notation) is a text-based data interchange format defined by RFC 8259, representing structured data with objects, arrays, strings, numbers, booleans and null. Its syntax derives from JavaScript object literals, but it is supported by nearly every programming language.
How it works
A JSON document nests key-value pairs (objects) and ordered elements (arrays); each language provides parsers and serializers to convert between the text and in-memory data structures. Valid JSON forbids comments, trailing commas and single-quoted strings.
Usage
JSON is the standard payload format for web API requests and responses, appears in configuration files such as package.json, and carries data in logs and message queues.
Related and confusable terms
Markdown targets human-readable formatted prose, while JSON targets machine-parsed structured data. HTML is a markup language for documents. Many APIs use JSON as their default data encoding.