How does Asp.Net Ajax Update Panels work
UpdatePanels have two ways of updating their contents: Always and Conditional. This can be set through the UpdateMode property of each UpdatePanel. The default value is Always which means that the UpdatePanel will refresh on each and every postback, regardless of what control it originated from.
The Conditional mode is much better. When set, the UpdatePanel refreshes only if one of the following conditions are met:
- A control inside the UpdatePanel (i.e. a child control) invokes a postback.
- A registered trigger is invoked (such as a button click outside the UpdatePanel).
- the Update() method for the UpdatePanel is called (through the server side code).
