Ajax Basic

AJAX allows you to send receive data without reloading whole page thus improving performance

AJAX Control Toolkit contains some useful tools to improve your website user interface

how can i know that it is doing so.

can u give me some tutorial on ajax controls

that will help me to learn ajax

Here's the official site with all controls and also their tutorials

http://www.asp.net/ajaxlibrary/AjaxControlToolkitSampleSite/

can we use open file dialoag in asp.net

i want to upload a pic can u give me example