If you use any type of popular weblog, CMS or personal publishing system you may be familiar with the term Trackback.

Trackback is a functionality first introduced by Movable Type and later supported by many other blogging and CMS technologies to allow for direct referencing between content items on different sites. Trackback was first released as an open specification in August 2002. It first appeared as a feature in Movable Type 2.2.

A great, official introductory guide to Trackback is available at Movable Type where a Full Trackback for Beginner's compiled by Movable Type author Mena Trott. The Guide clearly explains how and when to use Trackbacks touching even on present and future applications. Many screenshots illustrate how to actually perform a Trackback to another article.

In addition, at the Movable Type Web sitea whole page is devoted to document the adoption by the industry of the Trackback protocol.

Nonetheless the apparent simplicity and clarity of the above, if you ask most bloggers about Trackback they will look at you hopeful that you can yourself clarify for them what the heck is this thing supposed to be used for. Aren't links the same thing?

In response to my own need to understand and to help others make the best of what new communication technologies offer, I nhave written here a few simple explanations of what Trackback is and how it can be best used for yuor own publishing needs:

Trackback is a reverse link. Someone external to us sees one of our articles and says "well, this should have a link to my article over here". So he proceeds to add that link by the mechanism of trackback.

As simple as that.

In the future, who reads that article, even if it is not yours can also follow the link that has been added by trackback mechanism and arrive at your article too.

First of all here are some great excerpts from what Mena Trott wrote in the beginner's guide. This will certainly allow you to better understand the benefits of using Trackbacks:

1) Remote Commenting

"Currently, the main use of TrackBack is as a remote commenting system: if I post on my weblog about a post on your weblog, my weblogging tool will notify yours to inform you of that. Your weblog will then display the excerpt of the post that I made, with a link back to the post on my site. This allows visitors to your site (and you) to know what others are saying about your post--like comments, in other words, but the post is on my site instead of yours, as it would be if I had just left a comment. This gives me control over my post. If I want to fix a typo, or change some wording, then I can do that; whereas if I had left a comment on your site, I would not have access to change the text. In other words, TrackBack provides more control over your content.

The power of this method is that the TrackBack ping has created an explicit reference between my site and yours. These references can be utilized to build a diagram of the distributed conversation. Say, for example, that another weblogger posted her thoughts on what I wrote, and sent me a TrackBack ping. The conversation could then be traced from your original post, to my post, then to her post. This threaded conversation can be automatically mapped out using the TrackBack metadata. For example, this thread: http://www.sixapart.com/safari-thread.html. This is a diagram of the conversation started by this weblog post: http://www.sixapart.com/log/2003/01/initial_reactio.shtml."

2) Content Aggregation

"Although TrackBack's most prevalent use thus far has been as a form of remote commenting, a more exciting use has been emerging: using TrackBack to aggregate content into topic-based repositories. This was actually the original intended use of TrackBack--the remote commenting grew out of a special case of a topic-based repository, the "topic" being a single weblog post.

Content aggregation sites collect content about a particular topic. If you've ever tried to look for weblog posts about a particular subject, it's pretty much impossible to do, unless the subject is a news story or something timely. If your subject is something like 80's Music, you'd have a much more difficult time finding all weblog posts about that subject. This is where TrackBack comes in: by establishing a repository for posts about 80's Music, other content authors can use TrackBack to automatically ping this central category. Anyone looking for weblog posts about 80's Music can come to this page to find pointers to such posts.

These content repositories can be either centralized, like the Internet Topic Exchange (http://www.topicexchange.com/), or distributed. In Movable Type, for example, you can set any of your weblog categories to receive TrackBack pings--this enables you to transparently become a source of information on a particular topic of interest to you."

3) Controlling Content

"As time goes on and you invest more time and content into your weblog, you will likely want control over all of the content that you post on other weblogs and systems. For example, if you post your thoughts about a post on someone else's weblog, you'll want to post those thoughts on your own weblog, so that you are in control of them. Or, if you post a review on amazon.com, you may want this review to be syndicated on your own site.

TrackBack can be used to help with this. As an example, Matt Haughey's Posted Elsewhere sidebar (http://a.wholelottanothing.org/) aggregates content that he has written elsewhere. The reverse would also work: instead of posting the content on someone else's site, an author could post the content in his own weblog, then send a TrackBack ping to the other site. For example, if amazon.com reviews accepted TrackBack pings, you could control the content on your own site, and let amazon.com link back to you."

If that wasn't enough I thought of adding my view and up-to-date understanding of what Trackbacks are and how they can be best leveraged. This includes some relative innovative way of looking at what they do and what you can get done with them.

Trackback should be considered a facility that allows you to:
a) Create a collection of articles references. When you post anew article trackback other relevant articles and in the future your trackbacks will appear as additional references to consult. See for example the use of trackbacks at the bottom of:
http://robingood.typepad.com/commagents/2003/07/learning_suppor.html
b) Adding your content as an official reference to someone's else posts/articles. By trackbacking that content you add yourself to the related resources for that article in the blogosphere.
c) Calling attention of someone else to your post. By way of trackbacking other articles you inevitably send signals to the author of the trackbacked article saying: "Hey, look what I had to say about your post!".
One could then say that Trackback allows you to get links from authoritative resources on-demand. If there is an authoritative Web site out there and you send a trackback to one article on that site, you automatically get not only a physical link from that site to yours, but also but all of the indirect oexposure and reach of that very site itself.

How powerful if well used!

I know your first concern is: "But how do I avoid then people exploiting this in ways that I may not like?". The answer is simple enough. Authorities on the Internet, have already long understood this and have closed their option to receive trackbacks. They select voluntarily who to hand out a link and when.

Trackbacks are an authority-building mechanism which can be ethically exploited to rapidly leverage one's own expertise, visibility and exposure in the noosphere.

Here are the publishing tools that presently support Trackback:

Movable Type
Bloxsom - PHPoxsom
Blojsom
Nucleus
B2
Radio
TrackBack standalone Tool