We need to add validation rules while making web forms. It is used because we need to take inputs from the user in the right way like we need the right email address in the email input field. Some time user did not enter the correct address as we aspect. That's why we need validation.

Validations can be applied on the server side or the client side.

Server Side Validation

In the Server Side Validation, the input submitted by the user is being sent to the server and validated using one of the server-side scripting languages like ASP.Net, PHP, etc.

Client Side Validation

In the Client Side Validation, we can provide a better user experience by responding quickly at the browser level.

BY Best Interview Question ON 25 Jan 2019