TrackBack is a very neat new feature of my Weblog software. Here’s how it works. Imagine we both have weblogs. I post an entry that you want to comment on. But you have a weblog of your own, and would rather write what you have to say there. (Why scatter your genius across the web willy-nilly, when it can all be on your site?) So instead of putting a comment under the entry on my webpage, you write a regular log entry in your weblog and use trackback to ping the entry on my page that you want to talk about.
“Isn’t that just like linking to your site?” you ask. No—- because the ping causes a link to your new weblog entry to appear on my site. For us, it means we can carry on a conversation about something, each using our own weblog for our half of the conversation and then pinging the other’s. For other people who come across either of our sites, clicking on the trackback link for any entry shows links to all the other weblog entries that talk about that entry. In this example that’s just the two of us, but of course there can be lots of links—- in fact, the more the better.
Right now, trackback is only available on weblogs powered by Movable Type. But the ping format is an open standard and there’s no reason that other sites couldn’t use it. With only a few active users, there won’t be that much activity, but—- just like hyperlinking—- there are increasing returns to scale.