I must admit, although I use Wordpress as a base for most of my sites, I do not understand the "trackback" system. My Akismet plugin seems to do a good job of catching spam but I get quite a few of these notices that get posted to my system under comments where people really are just stealing my comment if you ask me and using the first part of my posts to fill up their fake blogs. I get a notice about it. I assume there is not much I can do about these fools stealing my content but should I allow their "pibgback" to be posted under my post comments?
A Trackback is a simple thing in wordpress which provides you a link with the site which has either used your link or either made a post with your link in their post. Taking example .. You have a blog at your url and I read your post and find it interesting I might link to your post and this link in the post will trackback your site indicating that I have linked to your site. Some people use feedwordpress or any auto blogging software to rely on feeds which automatically sends you trackbacks each time. If you want to remove it from your site , do not approve them at all or even remove the trackback code from your single.php file.