Form Validation Controls in Web Forms — a practical guide to Web Forms validation controls with clear examples you can reuse in real projects.
ASP & ASP.NET Tutorial Series (69/247). Prefer one article? Read the complete ASP.NET tutorial.
Short description
Enable client + server validation; always validate server-side.
Validator tip
<asp:RequiredFieldValidator ControlToValidate="Email" runat="server" ErrorMessage="Required" />