A TrackBack is a notification that another blog has made a post relevant to whatever is receiving the TrackBack.
Two main uses:
Notifying a blog that you've written a post that comments on a specific post in that blog
Notifying an aggregator that you've made a post that it should aggregate
An Echo element to support Trackback and other Entry-Entry links is discussed at Related.
entry-specific trackback URI: POST title, excerpt, url, blog_name; GET returns RSS of trackbacks
Within a specific log entry, RDF like the following is used:
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:trackback="http://madskills.com/public/xml/rss/module/trackback/"> <rdf:Description rdf:about="http://www.foo.com/archive.html#foo" dc:identifer="http://www.foo.com/archive.html#foo" dc:title="Foo Bar" trackback:ping="http://www.foo.com/tb.cgi/5" /> </rdf:RDF>