Server Control Form Validation
(April 29, 2005)
Introduction to Validation
The Web Forms framework includes a set of validation server controls that provide an easy-to-use but powerful way to check input forms for errors and, if necessary, display messages to the user.
Validation controls are added to a Web Forms page like other server controls. There are controls for specific types of validation, such as range checking or pattern matching, plus a RequiredFieldValidator that ensures that a user does not skip an entry field. You can attach more than one validation control to an input control. For example, you might specify both that an entry is required and that it must contain a specific range of values.
ASP.NET Validation Controls
(October 25, 2002)
If you've never had experience with ASP.Net validation controls then this article will shed light on them and teach you everything you need to know about them