If you are using Windows Authentication and want to avoid the login prompt which comes when you try to access the application this blog will help you. The solution I am writing below is only for IE.
In order to avoid that and let IE use the same credentials by which you are logged in into the Windows. Go to Tools -> Internet Option -> Security -> Custom Level -> Scroll the whole way to the bottom and select "Automatic Login with current user name and password” -> OK -> OK -> Close and reopen browser.
After that you won't see the prompt in IE.