Hyperlinks in the form of web links are the lifeblood of today's internet and world wide web. Examination of your web server's log files, either directly via tools such as Webalizer or indirectly via analytics services such as Yahoo's or Google's can show you who's visiting your web site or blogs.

But who's visiting your site isn't the whole picture; following a hyperlink is an active process. To complete the picture you need to find out who's linking to your site, which is a passive process.

If you're running a blog you may be able to use trackbacks or pingbacks to find out when a site links to you, but only if the linking site support the trackback or pingback protocol and then only if this is enabled on both sides of the ping relationship.

So what about those sites which don't support trackbacks or pingbacks or who don't want to be discovered that they're linking to you?