[1] It is one of four types of linkback methods for website authors to request notification when somebody links to one of their documents.
The TrackBack specification was created by Six Apart, which first implemented it in its Movable Type blogging software in August 2002.
Six Apart started a working group in February 2006 to improve the Trackback protocol with the goal to eventually have it approved as an Internet standard by the IETF.
Instead, Blogger provides "backlinks",[3] which allow users to employ Google's search infrastructure to show links between blog entries.
Some blogging tools are able to discover these TrackBack URLs automatically, others require the commenting blogger to enter them manually.