Find more about JSON on Wikipedia: https://en.wikipedia.org/wiki/JSON.

The JavaScript Object Notation (JSON) is an open-standard file format or data interchange format that uses human-readable text to transmit data objects consisting of attribute-value pairs and array data types (or any other serializable value).

JSON's basic data types are:

• Number: a signed decimal number that may contain a fractional part and may use exponential E notation, but cannot include non-numbers such as NaN. The format makes no distinction between integer and floating-point. JavaScript uses a double-precision floating-point format for all its numeric values, but other languages implementing JSON may encode numbers differently.
• String: a sequence of zero or more Unicode characters. Strings are delimited with double quotation marks and support a backslash escaping syntax.
• Boolean: either of the values true or false
• Array: An ordered list of zero or more values, each of which may be of any type. Arrays use square bracket notation with comma-separated elements.

• Object: an unordered collection of name-value pairs where the names (also called keys) are strings. Objects represent associative arrays [8], where each key is unique within an object. Objects are delimited with curly brackets and use commas to separate each pair, while within each pair, the colon ':' character separates the key or name from its value.

• null: an empty value, using the word null

Whitespace is allowed and ignored around or between syntactic elements (values and punctuation, but not within a string value). Four specific characters are considered whitespace for this purpose: space, horizontal tab, line feed, and carriage return. In particular, the byte order mark must not be generated by a conforming implementation (though it may be accepted when parsing JSON). JSON does not provide syntax for comments.

Via Display Pattern Editor

You find the JSON in the display pattern editor in JSON preview:

1. kind: shows the type of content, e.g., ContentDoc for content items or ListItemDoc for list items.
2. fileTransferId: shows all assigned contentPermissionSets
3. ownerTokenId: shows the id of the owner
4. contentType: shows the type of content, e.g., File or Virtual
5. backup information
6. contentSchemaId: is the underlying schema of type file type or virtual type with the assigned layers.
   1. In data, you find all available metadata values from the item
7. brokenReferenceIds, RelationTargetIds, and IndirectReferenceIds are for system checks to ensure data integrity. You can use those fields to check for any broken references in the system to fix them.
8. lifeCycle: is the state of the item, whereas inactive items are no longer available in the system
9. id: the ID of the item which is also shown in the URL when opening the item in the item detail view
10. docType: refers to the kind and the corresponding index in the database, e.g., ContentDoc or ListItemDoc
11. audit: shows information about creation and modification.

Via Developer Tools

You can see the JSON of an item by{ opening up the item detail view and check in the developer tools (Chrome F12) in the network the response for the corresponding item, shown as id: