One area of Web Forms that has not been covered yet are Validation Controls. These web controls are used to perform validation against any other control in a Web Form. In total, there are six validation controls:
RequiredFieldValidator— Used to ensure that a specified control has been filled out.
CompareValidator— Used to compare the value of a control against another value.
RangeValidator— Used to ensure that data entered into the control falls between a range of values.
RegularExpressionValidator— Used to check the formatting of a control’s value against a regular expression string.
CustomValidator— Used to validate the value of a control against a custom validation routine or logic.
ValidationSummary— Used to display ...