How to do a post back when user press enter.

In a regular html form, when user press "enter" key, the form will be
submitted.

However, in ASP.NET web form, a form will only be submitted (post back) when
a special button is clicked. Many user get used to click "enter" key to
submit a form. How can I use "enter" key to submit/postback in ASP.NET.

Thank,

Guoqi Zheng
http://www.ureader.com
.