Other people can link our images or other website elements from our website and thus our server will need to serve this content for their websites.

To prevent this "hotlinking" one can add following code into .htaccess file in their website root folder (same folder where index.php is)

RewriteEngine on
RewriteCond %{HTTP_REFERER} !^http(s)?://(www\.)?YOURDOMAIN.TLD [NC]
RewriteRule \.(jpg|jpeg|png|gif|mp3|swf|css|js)$ - [NC,F,L]