Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. JSON, short for JavaScript Object Notation, is a lightweight computer data interchange format. It is a text-based, human-readable format for representing simple data structures and associative arrays. The JSON format was originally specified in RFC 4627 by Douglas Crockford. The official Internet media type for JSON is application/json. The JSON filename extension is .json. The JSON format is often used for serialization and transmitting structured data over a network connection. Its main application is in Ajax web application programming, where it serves as an alternative to the XML format. Although JSON was based on a subset of the JavaScript programming language and is commonly used with that language, it is considered to be a language-independent data format. Code for parsing and generating JSON data is readily available for a large variety of programming languages. The json.org website provides a comprehensive listing of existing JSON bindings, organized by language.