UpdatePanels on a Page

1. By default, an UpdatePanel control is refreshed when either one of its child controls causes a postback or another UpdatePanel in the page is refreshed. This behavior can be altered with some public properties—namely UpdateMode, ChildrenAsTriggers, and Triggers.

2. If there are multiple update panels on a page, if one gets refreshed the other would also get refreshed.

a. This is because the UpdateMode of the update panel is set to "Always" by default. You can set it to "Conditional" to refresh conditionally and not always.

b. The ChildrenAsTriggers property is a Boolean property (true by default) that determines whether child controls of a panel act as triggers of AJAX postback events.

3. Have smaller panels that bring back just the minimum amount of markup you need for that particular click.