JSON is the acronym “JavaScript Object Notation”. Having perused through a few sites, I have come across this topic many times and have no idea what this was. So here are some links to get started:
Matthew Batchelder gives the case to use JSON above XML. Obviously, JSON is more readable compared to XML. (Going through a large XML file is kind of a headache.) Using JSON avoids parsing XML since it is already recognized as a data structure. Thus avoiding the XML process would give the benefit of speed.
The JSON site includes some Actionscript libraries (in AS1, AS2, and AS3) to implement it in your code.
DJ