asp.net validation basics

basic article from msdn


<asp:RequiredFieldValidator 
   id=thisValidatorControlId
   ControlToValidate=controlToValidateId
   ErrorMessage="UserName is a required field." 
   EnableClientScript=true 
   Display=None Runat=server/>

<asp:ValidationSummary 
   id=ValSummary 
   HeaderText="The following errors were found:" 
   ShowSummary=True 
   DisplayMode=List 
Runat=server/>

RequiredFieldValidator
RangeValidator
CustomValidator
ValidationSummary
RegularExpressionValidator

See here for a summary of the validation controls