From http://json.org/

JSON (JavaScript Object Notation) is a lightweight data-interchange format. It is easy for humans to read and write. It is easy for machines to parse and generate. It is based on a subset of the JavaScript Programming Language, Standard ~ECMA-262 3rd Edition - December 1999. JSON is a text format that is completely language independent but uses conventions that are familiar to programmers of the C-family of languages, including C, C++, C#, Java, JavaScript, Perl, Python, and many others. These properties make JSON an ideal data-interchange language.

In TiddlyWeb, JSON is the most frequently used representation. All resources that are returned as JSON have Content-Type of application/json. To GET JSON make a request with an Accept header of application/vnd.tiddlyweb+json. To PUT a resource with a JSON representation make a request with a Content-Type header of application/vnd.tiddlyweb+json.