JSON, or JavaScript Object Notation, is a lightweight data format used for storing and exchanging data. It organizes information in key-value pairs, making it both human-readable and machine-friendly. 

JSON is commonly used in APIs, web applications, and configuration. It supports objects, arrays, numbers, strings, and booleans. JSON’s simplicity, flexibility, and compatibility with most programming languages make it a popular choice for data serialization and communication across platforms.