XML and JSON — Advantages and Disadvantages?

I recently heard about JavaScript Object Notation (JSON), and after looking it up, it seems like it's becoming rather popular as an alternative to the Extensible Markup Language (XML).

I went on this page for more info, but it seemed more of an XML-bashing page rather than a comparison page. So I thought I should ask here:

What are the benefits of JSON as compared to XML, and why (if at all) should we choose one over the other?