AJAX
From ByteWiki
AJAX: Asynchronous JavaScript and XML
Hidden Frame Technique
The hidden frame technique is where AJAX got it's start. Using a standard frameset with a invisible frame(width or height of 0) enabled 2(or more) pages to be open at the same time while only one of them was visible. When the user made some action on the client side that needed some extra information from the server, using javascript you could control the location of the 'hidden frame' to get that information from the server.
This http request could be used for e.g. to open a file 'searchFor.php?id=1234' You could then get current information from a database or whatever.. on that item with id '1234' and return it to the visible frame using javascript.
Typically when the page is loaded and all the data is gathered(onLoad event) the javascript returns the relevant data to the visible frame and displays it in a nice helpful way.
