what is update panel in ajax? why do we use update panel. any advantages and disadvantages?

Kindly refer following links
http://stackoverflow.com/questions/1151821/advantages-and-disadvantages-of-using-ajax-update-panels-in-asp-net-application.
http://encosia.com/why-aspnet-ajax-updatepanels-are-dangerous/

Rajesh Patel
MCPD,MS
Brainbench (Asp.Net 4.0 and CSS 3.0)

1.ASP.NET UpdatePanel controls enable you to build rich, client-centric Web applications. By using UpdatePanel controls, you can refresh selected parts of the page instead of refreshing the whole page with a postback. This is referred to as performing a partial-page update.

2.When you use an UpdatePanel control, the page behavior is browser independent and can potentially reduce the amount of data that is transferred between client and server.

Thanks to all...

Thanks & Regards
Hari