What is Trackback link?
A trackback is one of three types of linkback methods for website authors to request notification when somebody links to one of their documents. This enables authors to keep track of who is linking to their articles.
Trackback is a means for one Web page to let another Web page know that it's been linked to. If that sounds simple but confusing, here's an example usage.
The trackback script can be used to send a trackback pings to any blog that accepts Trackbacks. You do not need to have a Trackback system on your blog to send pings. After submitting the form the results will be displayed.
Let's say Wendy writes a post on her Web site and enables Trackbacks on that post. In essence, what Wendy has done is said, "ok, I've said something and now I'm listening." Fred reads Wendy's post. He writes a post on his site that links to Wendy's post. Fred can then send Wendy's post a Trackback ping that contains information about Fred's post. In essence, Fred is saying, "hey Wendy, I heard what you said and here's my response." Since it is Trackback-enabled, Wendy's post is then modified to include a link to Fred's response. In this way, Wendy can aggregate responses to her post, people who have read Wendy's post have a way of letting her know they've responded, and anyone who reads Wendy's post can click through and read those responses.
Trackbacks provide a way for two blogs to cross-pollinate their readers. If you don't have a lot of readers, writing a good post, refering to another's post, and trackbacking might entice some to come to your blog. If they like what they see, they might return.
Beware of Trackback Submitter
Trackback Submitter is one of most popular link building tools used by spammers and users of black hat SEO. It abuses the feature called Trackback which allow bloggers to request notification when somebody links to one of their documents. Developed by an unknown spammer from Europe in September 2006, Trackback Submitter became very popular because of its ability to bypass comment spam protection used on popular blogging systems like Wordpress. If you own WordPress blog, beware of this company and their services. I would also recommend keeping a distance from their customers as well.
Some Trackback servers block pings unless they come from the same place as your blog is hosted. If you get an "unspecified error" then that's probably what's happening. Spammers ruin everything.