Stands for "JavaScript Object Notation" and is pronounced like the name "Jason." JSON is a text-based data interchange format designed for transmitting structured data. It is most commonly used for transferring data between web applications and web servers.

JSON is often viewed as an alternative to XML, another plain text data interchange format. In most cases, the JSON representation of an object is more compact than the XML representation because it does not require tags for each element. Below is an example of an object named "Gaming PC" defined in both JSON and XML.


  "computer": {
    "name": "Gaming PC",
    "components": {
      "cpu": "Intel i7 3.4GHz", "ram": "16GB", "storage": "2TB HDD"


  <name>Gaming PC</name>
    <cpu>Intel i7 3.4GHz</cpu>
    <storage>2TB HDD</storage>

As you can see, the object is represented more efficiently in JSON than in XML. JSON's efficiency has helped it become a popular choice for web applications and is it is now often used in place of XML. Even Ajax applications commonly use JSON, though Ajax technically stands for "Asynchronous JavaScript and XML." While the difference between XML and JSON may be negligible for small applications, JSON's low overhead can help reduce bandwidth and other system resources used by high-traffic websites.

File extension: .JSON

Updated November 8, 2011

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