I've heard that JSON serializes all the data, which stops me having problems client side in terms of cross-browser support etc..
I've been using AJAX with jQuery and it seems easy, but I'm unsure of the differences,
I've read I can also use this to get the data:
I think you are confusing the terms.
JSON is just one of these formats. It's a data interchange format, where-as AJAX is a technique to communicate with a server after the initate page load has completed.
To answer your question on whether you need to specify the
dataType; jQuery will best guess the response format (be it HTML or JSON etc), so you're usually fine to omit it.