3.7 Postback Versus Non-Postback Events
Postback events cause the form to be posted back to the server immediately. These include click-type events, such as Button.Click. In contrast, many events (typically change events) are considered non-postback because the event is not posted back to the server immediately. Instead, these events are cached by the control until the next time a post occurs. Controls with non-postback events can be forced to behave in a postback manner by setting their AutoPostBack property to true.
Table 3-3 summarizes the controls with postback and non-postback events.