JSON (JavaScript Object Notation) is a lightweight, text-based data interchange format that uses human-readable key-value pairs and ordered lists to represent structured data. Originally derived from JavaScript, JSON has become the de facto standard for web APIs and configuration files across virtually all programming languages. While its syntax is deliberately minimal—supporting only six data types and disallowing comments or trailing commas—this simplicity ensures universal compatibility and predictable parsing. Understanding JSON's core rules, escape sequences, and edge cases around number precision, circular references, and encoding enables developers to work confidently with APIs, config files, and data pipelines.