In case you've been living under a rock, JSON is a lightweight data-interchange format that kicks booty. It is super-easy to consume and makes for a data format that we can all love and tuck under our pillow each night. If you find your are storing data in some hard-to-manage format, it's time to open your heart and let JSON into your life...all the cool kids are doin' it!
Remember back in the '80s how everyone wanted a fax machine, but they weren't quite sure what to do with it? Same for AJAX. If you are not sure why you need it, you don't need it. But, if you find that you are trying to serve up data in pages on user-driven events such as mouse-over, AJAX might just breathe some life into your oh-so-1997 web page. There are some considerations with regards to SEO, but if we take a moment to think things through, we can implement AJAX-driven components in your web site that keep the full page refreshes to a minimum, satisfy the SEO gods, and turn visitors into customers.