Changing a Variable without reloading the page

Very useful information, now works a treat, thanks! :)

what is a code example of this, I have read loads of explanationson this forum. Seen no examples thou.

What would the code be to..

Grab variables from PHP, I'm guessing with an external PHP file (the php will update, no need to worry about the PHP code, I can do that).

Then update a div on a html page with AJAX ?

Thanks,

Jamie