The idea of detecting links to your web page and then automatically generating a link to anyone who has linked to you. In other words, all incoming links are turned into BidirectionalLink''s. This term has not yet acquired a canonical name in the user community (maybe hypertext academics have a canonical name, though, I wouldn't know). One other name for it is "reflective link".

See also ExternalBackLink.

[CategoryWebTechnology]

This is also called referrer tracking. You can't just list all referrers, because not all of them actually link to the page. You have to visit that page and check. If it really links, then link back to it.

This can also be exploited using so-called referrer spam. A porn site can link to your site, relying on your link back to it. The porn site might hide the link using CSS, so machine based link verification might not always work.

Another thing to avoid are search results. You usually don't want to link to the Google query that led to your site. One solution is to maintain a blacklist of regular expressions, perhaps using FileReplacement.

Automating your backlinks can have it's advantages and disadvantages. Make sure if you implement this you are aware that you are opening your site up for spam. [Back Links]

See also BackLink for internal backlinks.

Implementations

• OddMuse has this, including a special page where you can list regular expressions matching spammers and search engines. This requires manual maintenance of the the blacklist. http://www.emacswiki.org/cgi-bin/oddmuse-en.pl/Automatic_Link_Back
• TinyWiki
• UseMod:WikiPatches/AutomaticLinkBack

It should be possible to use Google or other search engines for this:

• http://www.google.ch/search?as_lq=http%3A%2F%2Fwww.usemod.com%2Fcgi-bin%2Fmb.pl%3FAutomaticLinkBack

Tools

• [Disenchanted list of AutomaticLinkBack tools]
• [Stephen Downes' referer service] Finds BackLinks for the last 24 hours; uses a script hosted at Stephen Downes' site.''
• [Dive Into Mark's system] (see also [Dive Into Mark:further_reading_upgrades])
• TrackBack -- MovableType and other (mostly WebLog) systems
• [Pinseri's Movable Type Backlinks] -- superceded by TrackBack
• [PingBack] -- based around the poster's blog sending an XML-RPC "ping" to the blog it's linking to, telling it what was linked to and where the link comes from.
• [Laze.net's system] -- PHP
• [Phil Ringnalda's code] -- PHP
• [Scott Wilson's Referrer zClass] -- Zope
• [Waxy.org's CGI script] -- CGI and also PHP compatible