A JSON (JavaScript Object Notation) file is a lightweight, text-based format used for storing and exchanging data. It structures information in a readable way using key-value pairs and ordered lists, similar to basic programming language objects. Unlike complex formats like XML, JSON prioritizes simplicity and ease of parsing, making it highly popular for web applications and configuration.

Developers primarily use JSON files to transfer data between servers and web clients in APIs (Application Programming Interfaces). For instance, when you see live updates on social media feeds like Twitter or Facebook, JSON files often carry that new post data between the server and your browser. JSON is also widely used for storing configuration settings in applications like Visual Studio Code or defining structured data for tools like npm (Node Package Manager).

Key advantages of JSON include its human readability, wide programming language support, and minimal syntax overhead, enabling efficient data transfer. However, limitations include lack of support for complex data types like dates directly and no built-in mechanism for schema enforcement or data validation. Despite these minor limitations, JSON's simplicity ensures its continued dominance in web development and data interchange.