PL/JSON is a generic JSON object written in PL/SQL. Using PL/SQL object syntax, users instantiate a JSON objects and then add members, arrays and additional JSON objects. This object type can store JSON data, in Oracle, persistently.
Who wrote PL/JSON?
Lewis Cunninghham
Why and when would I use JSON?
JSON is a format for exchanging data. It's simpler to use than XML and is smaller. There are many places on the web to read about XML vs JSON. A very good place is JSON.org. Another good article, that fully explains RESTful web services, is from IBM: RESTful Web services: The basics