Verification: Verification is a process to ensure that the software that is made, matches the original design. In other words, it checks whether the software is made according to the criteria and specification described in the requirement document. It is to check whether you built the product right as per design. It is a low level checking. (It is done in walk-through meetings generally). It checked whether it is made accordingly to the design..

Validation: Validation is a process to check whether the product design fits the client’s need. It checks whether you built the right thing. It checks whether it is designed properly.

The following validation controls are available in ASP.NET AJAX 4.0:

        => FilteredTextBoxExtender - Enables you to apply filtering to a text box.

        => MaskedEditExtender and MaskedEditValidator - Restricts a user to enter only a certain pattern of characters in the TextBox by applying a mask to the input.

        => ValidatorCalloutExtender - Attaches to the ASP.NET validators so that the error messages are not displayed as a simple text but as a balloon-style ToolTip.

        => NoBot - Prevents the spam/bot from filling the input forms automatically and uses the Completely Automated Public Turing test to tell Computers and Humans Apart (CAPTCHA), which is a type of challenge-response test to ensure that the response is not generated by the computer.

        => PasswordStrengthExtender - Measures the strength of the password text entered within the text box by validating with the different strength specified parameters

Validation controls are responsible to validate the data of an input control. Whenever you provide any input to an application, it performs the validation and displays an error message to user, in case the validation fails.

ASP.NET 4.0 contains the following six types of validation controls:

   => CompareValidator - Performs a comparison between the values contained in two controls.
   => CustomValidator - Writes your own method to perform extra validation.
   => RangeValidator- Checks value according to the range of value.
   => RegularExpressionValidator - Ensures that input is according to the specified pattern or not.
   =>  RequiredFieldValidator - Checks either a control is empty or not.
   => ValidationSummary - Displays a summary of all validation error in a central location.