JSON is a data interchange format

JSON is short for JavaScript Object Notation is a compact format for exchanging data. It was defined in 2005 by Douglas Crockford. The basis is a subset of the JavaScript programming language, the JavaScript Notation for Object Literals. JSON is now used everywhere in web apps. JSON is not a programming language, but instead a format for data exchange between different programming languages. JSON is versatile to use and human-readable. It is based on the JavaScript language core ECMA 262 from 1999.

JSON is based on JavaScript

Because JSON is based on JavaScript, various JavaScript editors or frameworks such as jQuery have JSON included as default. JSON is also used in web services as a service that supports interactions between two applications. Normally, messages exchanged within are based on XML. However, JSON code can also be used as an alternative. In comparison to XML, JSON syntax is easier to read and understand. An advantage for developers is also the fact that JSON objects are the same as JavaScript code except for a few exceptions. You will not need to work in complex syntax to use it. Its most common application is for the exchange of data between browser and server. Because JavaScript is often used here, it is very easy to use JSON objects.

You can find more information on JavaScript Object Notation on Wikipedia: https://en.wikipedia.org/wiki/JSON

and on the introduction page for JSON: http://json.org/index.html