I need to know how to do something, so help or links to tutorials or even just a name of what the technology is called would be awesome

Check out www.yahoo.com
The newly updated homepage sports a neat info box in the center of the page at the top.
It defaults to the 'featured' tab, but you can click on 'entertainment', 'sports' or 'life' and it changes only the content in the box - not the whole page.

Now, I'm guessing this is AJAX/Javascript, but I don't know where to start to recreate a similar thing for myself.

Over to you guys. If you can help I would really appreciate it!