function verify_credentials() {
        <?php
            session_start();

            //Connect to database.
            include("connect.php");

            $email = $_POST["email"];
            $password = $_POST["password"];
            $admin = $_POST["admin"];

            //Query the database for login details.
            $query = "SELECT * FROM CSC2043_users WHERE email='$email' AND password='$password'";

            $verify = mysqli_query($conn, $query) or die(myqli_error($conn));

            //If there is a match in the database.
            if(mysqli_num_rows($verify) > 0) {

                //Create a session for the user.
                $_SESSION['user'] = $email;
                header("Location: profile.php");
            } else {

                //Invalid input. Enter details again.
                header("Location: login.php");
            }

            mysqli_close($conn);
        ?>
    }