<?php

function get_gravatar($email, $size = 80, $defaultImageSet = 'mm', $rating = 'g')
{
    $url = 'https://www.gravatar.com/avatar/';
    $url .= md5(strtolower(trim($email))).'?';
    $params = [
        's' => $size,
        'd' => $defaultImageSet,
        'r' => $rating
    ];


    return $url. http_build_query($params);
}

?>

<img src="<?= get_gravatar('witalimik@web.de') ?>">