What are weblog trackbacks and why should I include them on my blog?

Trackbacks -- also known as pingbacks in some blogging applications -- started out as an ingenious method of having two different Weblog articles cross-reference each other automatically. It's best explained by example. Say you'd written an article on your site about trackbacks. I could point to it here on my Weblog with an explicit link, then people who read my article could ostensibly click through and read your piece too. If someone started out at your site, however, they'd never know that I also wrote about the same topic and that I had linked to your article.

So what if when I submitted my article to my Weblog management system (Movable Type, in this case) it automatically notified your Weblog that I'd included a link to your article within my own? That's useful because you definitely want to know what people say when they respond to you and link to your article.

The next level of sophistication, though, is for your Weblog management system to automatically include a pointer to my article at the end of your own article, so that people who start out on your site know that I've written a response or reaction to your article on my site too. Smart and sophisticated, a real proof of the dynamic and fluid nature of information publishing in the 21st century, right?

And yet you can't trust trackbacks because software doesn't differentiate between your legitimate weblog article linking to my own and a spammer sneaking in more inbound links to their site with spoofed trackback pings. I kid you not. In fact, just this weekend I got a trackback ping on one of my other weblogs that looks legit, but isn't:

prom and homecoming dresses
Excerpt: That sounds basically right. What do I know 
though, i run a silly designer prom dress site.
Weblog: Prom Dress Patty
Tracked: January 16, 2005 01:23 PM

If you were click through to the site link (which I haven't included because this person doesn't deserve the link) you'd find that it actually points to the home page of a cheesy ecommerce site and there's not only no article, there's not even a weblog involved.

You can read this and see it's obviously a bogus link (the fact that it has nothing to do with the article it's "trackbacking" is a pretty overt clue), but my Weblog system dutifully added it to the trackback links page and gave these losers a new inbound link from a popular, high PageRank site. At least, until I deleted it.

The other issue with trackback pings is the same one that plagues Web sites with little counters on the bottom of the page. Don't you think about the site differently when you see "You're visitor 36" than if you see "You're visitor 137597" at the bottom? Of course you do, because more links, more comments, more trackbacks are all an indication of popularity, and popularity piques public interest in a circular sort of way. So some sites play down the trackback links because, well, they just don't want to say "no-one responded to this article in the entire blogosphere", "no-one responded to this one either", etc etc.

That should tell you why these trackback links appear in various spots -- if at all -- on different weblogs. With many weblog tools the author has control over where or if it appears, but with others it s stuck and you just have to hope that you can delete the trackback spam before one bogus one attracts a herd of others and subsumes your thoughts and earnest writing completely.

As an ironic post-script, I actually just turned off the trackback feature completely on the blog in question, because I'm not using it much anyway, and, well, it never got into the public eye and never saw many legitimate trackback pings anyway.