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A linkback is a method for Web authors to obtain notifications when other authors link to one of their documents. This enables authors to keep track of who is linking to, or referring to, their articles. The four methods (Refback, Trackback, Pingback and Webmention) differ in how they accomplish this task.
"LinkBack" is the generalized term used to reference three methods of communication between websites.
Any of the four terms—Linkback, Trackback, Pingback, or (rarely) Refback—might also refer colloquially to items within a section upon the linked page that display the received notifications, usually along with a reciprocal link; Trackback is used most often for this purpose. Also, the word Trackback is often used colloquially to mean any kind of Linkback.
Dan Magarino, Morgan Stanley Equity Research, is credited with popularizing the term "linkback" and also contributed to its widespread adoption by RiXML.org.
|Trigger mechanism||Visitor to linking site clicks on the link, and his browser takes him to the linked site||Code on linking server examines added or updated documents, extracts links, and sends notification to linked server for each link found||Code on linking server examines added or updated documents, extracts links, and sends notification to linked server for each link found||Code on linking server examines added or updated documents, extracts links, and sends notification to linked server for each link found|
|Notification medium||HTTP referrer value||HTTP POST||XML-RPC call||HTTP POST with source and target parameters|
|Capture mechanism||Examination of incoming HTTP referrer values||Trackback capture script||XML-RPC function||Webmention capture script|
|Information sent by linking server||None||
|Additional information presented to linked server||HTTP referrer sent by a visitor's browser upon clicking the link||IP address of linking server||IP address of linking server||IP address of linking server|
|Autodiscovery mechanism (how the linking server finds out how and where to send the notification)||None||LINK tag in the header of the linked page or Trackback RDF Documents||Special HTTP header or LINK tag on the linked page||HTTP Link header or link element on the linked page|
|Action required when notification is received||
||Verifying that linking page does indeed link to linked page is recommended, not explicitly required|
|Advantages||Requires no special code on linking server (the link itself becomes the notification when someone clicks on it)||All the information desired by the linked server (Linking site name, post title, excerpt) is present in the notification itself||