JavaScript Object Notation, or JSON, is meant as a light weight alternative to XML when XML is just a bit heavy weight for what you are trying to achieve. Although JSON is not extensible, as it makes use of a fixed set of data types, it can be used to textually represent complex objects. JSON is a perfect data-interchange format when using technologies such as AJAX as your server side objects can be converted to JSON, sent to the client, evaluated in a client script and then manipulated to build dynamic adverts, menus etc.
This project provides a lightweight library, written in C#, for both parsing and generating data in the JSON format.