Validate user input in a Microsoft ASP.NET Web form, by using the ASP.NET validation controls.
Determine whether to perform user input validation at the client or the Web server.
As with Windows Forms applications, validating user input in a Web Forms application is an important part of any system. With Windows forms, you have a limited choice of where the validation should be performed—you check that the user's input makes sense by using events attached to the controls and forms of the application itself. With Web forms, there is an additional complication that you must consider: should you perform validation at the client (the browser) or at the server? In this chapter, you will examine this question and discover the options that are available to you.