# What is JSON?

JSON, or JavaScript Object Notation, is a minimal, readable format for structuring data. It is used primarily to transmit data between a server and web application, as an alternative to XML. Squarespace uses JSON to store and organize site content created with the CMS.

## Example

Append `?format=json-pretty` to the URL of any page on your Squarespace site and you'll be able to [view the JSON data](/view-json-data) for the site.

## Keys and Values

The two primary parts that make up JSON are keys and values. Together they make a key/value pair.

* **Key:** A key is always a string enclosed in quotation marks.
* **Value:** A value can be a string, number, boolean expression, array, or object.
* **Key/Value Pair:** A key value pair follows a specific syntax, with the key followed by a colon followed by the value. Key/value pairs are comma separated.

Let's take one line from the JSON sample above and identify each part of the code.

```js
"foo" : "bar"
```

This example is a key/value pair. The key is "foo" and the value is "bar".

## Types of Values

* **Array:** An associative array of values.
* **Boolean:** True or false.
* **Number:** An integer.
* **Object:** An associative array of key/value pairs.
* **String:** Several plain text characters which usually form a word.

Numbers, booleans and strings are self-evident, so we'll skip over those sections. Arrays and Objects are explained in more depth below.

### Arrays

Almost every blog has categories and tags. In this example we've added a categories key, but the value might look unfamiliar. Since each post in a blog can have more than one category, an array of multiple strings is returned.

```js
"foo" : {
  "bar" : "Hello",
  "baz" : [ "quuz", "norf" ]
}
```

### Objects

An object is indicated by curly brackets. Everything inside of the curly brackets is part of the object. We already learned a value can be an object. So that means "foo" and the corresponding object are a key/value pair.

```js
"foo" : {
  "bar" : "Hello"
}
```

The key/value pair "bar" : "Hello" is nested inside the key/value pair "foo" : { ... }. That's an example of a hierarchy in JSON data.

## Recap

We said at the beginning of this tutorial that JSON is a minimal data format. Just by learning a few key principles you can decode an entire site's worth of JSON. And now you can apply that knowledge to [developing Squarespace sites with JSON-T](/templating-basics), the template language behind the Squarespace Developer platform.