JSON is an acronym for Javascript Object Notation. It's a format for exchanging data with Javascript code. Additionally most programming languages have libraries that can parse JSON data. Compared to processing RSS/XML, JSON has less overhead and it's easier to use.
Retrieve a list of calendar the user can view:
http://calendar.yourdomain.com/jsonp/calendar_id/list.js
Retrieve the next 7 days of events from a specific calendar.
http://calendar.yourdomain.com/jsonp/calendar_id/3.js?dayspan=7
Retrieve a maximum of 12 events for a specific resource and send it to a Javascript function named MyCallbackFunction:
http://calendar.yourdomain.com/jsonp/resource_id/3.js?callback=MyCallbackFunction&maxcount=12
See Also: Remotely Extracting Data, Filtering on Multiple Options