Hotlinking (also called file leeching, remote linking, direct linking, bandiwidth stealing or bandwidth banditism) is a term used for describing a situation when a web page of one domain owner is directly linking to images (or other multimedia files) on the web host of another domain owner, usually using an <IMG> tag. If your domain is hotlinked, you may face the problem of excessive bandwidth usage.
To protect your domain from hotlinking: