Hi, I have a login page. User first enters information and submits the form. And I have a php script that will see if the user exists. If( authenticated == true) { // I do a redirect } else { // I want to popup an error message on the same page. } 1) I'm not sure how to show the popup message, I would like to make my div element visible with an error message returned from the server, I would have to use Ajax, right? But how? Or are there alternatives which are just as good.