Error validating user
DTHML and scripting languages improve things somewhat.
It is possible to provide the user with immediate feedback on bad input and to prevent them from posting a page until it has been corrected.
NET and walks through an example of adding validation to a page.Each time you get a request, you need to write code to check the input and write any errors the user has made back to the page to help the user to correctly fill in the form.This is a taxing process for end users, developers, and servers alike.The Validation Summary automatically generates this content by gathering it up from validator controls on the page. It exposes the all-important "Is Valid" property, which you check in server code to determine if all of the user input is OK.Most Web sites do all of their validation checks on the server.