<?php if (isset($_POST['submit'])){ $username = filter_input(INPUT_POST, "username", FILTER_SANITIZE_SPECIAL_CHARS); echo "Hello {$username}"; } ?> <!doctype html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0"> <meta http-equiv="X-UA-Compatible" content="ie=edge"> <title>Document</title> </head> <body> <form action="index.php" method="post"> <input type="text" name="username" id="username"> <input type="submit" name="submit"> </form> </body> </html>