If you run a site heavy on images (or even just a popular site that people might grab the images from), you're all too familiar with the practice of "hotlinking" - the linking to of your images from other sites. Well, if you think there's not much you can do about it - you're wrong, and this new article from A List Apart proves it.

Most web professionals are all too aware of the problems caused by hotlinkers. Leechers. Bandwidth thieves. People who use images hosted on your web server on their own pages.

The usual approach is to instruct the server to deny all requests for images where the HTTP referer header 1 is not either from your own site (or blank). Thus, only people actually browsing your web site - or those whose browsers are not passing referrer headers for whatever reason - will be able to see the image. The trouble with these techniques is that regular linking is also prevented. The solution I'm about to suggest solves this problem while giving credit to you when people link to your pictures.

The article continues on, stepping you through the creation of both a PHP script and some mod_rewrite rules to make the setup as simple as possible. Once in place, it can reduce almost all of the "theft" of your images for another's use...