TrackBack is a mechanism used in a blog to show, around an entry, a list of other blogs that refer to it.

The term TrackBack was introduced by Six Apart which introduced a mechanism in their blogging server, Movable Type, that works by sending a 'ping' between the blogs, and therefore providing the alert. The blog receiving the ping typically displays the TrackBack information below a blog entry. This usually includes a summary of what has been written on the target blog, together with a URL and the name of the blog. The Referer field in the HTTP protocol was originally intended as a means of supporting features similar to those TrackBack offers.

Some individuals or companies have abused the TrackBack feature to insert spam links on some blogs. This is similar to comment spam but avoids some of the safeguards designed to stop the latter practice. As a result, TrackBack spam filters similar to those implemented against comment spam now exist in many weblog publishing systems.

• Pingback

• A Beginner's Guide to TrackBack
• TrackBack Development
• Official specification
• What is Trackback? by Tom Coates
• All about Trackbacks and Pingbacks with Wordpress by Mike
• HaloScan Trackback - Free trackback tools (receiving and sending)
• Trackback Validator Plugin for WordPress: Trackback spam blocker
• Trackback wizard: execute a manual trackback, if your blog software does not support it.