The MIME type application/json is used to indicate the encoding for the file type JavaScript Object Notation or JSON. The category of the MIME type is "application".

This file type is a data interchange format that is text-based, lightweight and language-independent. This format was derived from a subset of the JavaScript programming language � the ECMAScript standard. This is the standard that defines the object literals of JavaScript that were used in the JSON format. JSON is used for carrying small sets of formatting rules to aid in the portable representation of structured data. It is essentially a text format made for serializing structured data.

The JSON format finds its main use in Ajax web application programming where it replaces the XML format. It is commonly used with the JavaScript language. A great number of programming languages have readily available code for generating and parsing JSON data, which is what makes the format so very viable and language-independent.

Even though the intended use for JSON is as a data serialization format, being a JavaScript subset renders it vulnerable to security issues. The main problem is centered on data retrieved from the Internet where a JavaScript Interpreter will dynamically execute the JSON text as JavaScript, exposing the system to possible malicious code.