A cross referencing system between blogs that was introduced in the Movable Type blogging software in 2002. When you make a comment on your blog about a subject posted on another blog, TrackBack is used to enable that blog to link back to your comment on your blog. It also allows a title and excerpt of the comment to be included with the link.
Both blogs must use blogging software that supports the TrackBack protocol. The TrackBack is initiated by selecting a link in your blog and filling in a title and excerpt. The software contacts the blog to see if it will accept a TrackBack. See Pingback