Setting a default button on a Web Form in ASP.NET 2.0
In ASP.NET 2.0, you can now set a default button on a page so that when the user presses the Enter key the button is automatically invoked.
For example, you have a page with two TextBox controls and two Button
controls. You can configure the Submit button to be the default button so it is automatically clicked when a user presses the Enter key. To set the default button of form use
< form id="form1" runat="server"
defaultbutton="btnSubmit">