This feature has a great impact on wikis, to make them more userfriendly.
Typically, though, if you've implemented BackLinks, you've already implemented some internal bidirectional link mechanism, whereas most other systems only allow direct creation of ForwardLinks.
The motivation to focus the topic is given in: Wiki:BidirectionalLink
From my own experience I feel, that a mechanism for automatically creating bidirectional links between different wikis would greatly enhance InterWikiing.
BidirectionalLinks are better, no doubt, even in data models and every day coding, you might want to know from any item in the system which other items are dependent on it.
But how does it work with links between systems? Let's say a link between two wiki's. Wiki 1 links to a page on wiki 2, so how can wiki 1 register it's page as a BackLink in wiki 2? And if the link ceases to exist, wiki 2 needs to unregister the BackLink in wiki 2? What if wiki 1 just ends it's existance and doesn't unregister with wiki 2? I guess the multiple of questions raised explains why ForwardLink""s were chosen over BidirectionalLink""s. -- StijnSanders
Another name is the ABC link. Some say having more weight on search engines. This is a link trading practice involving three sites instead of just two. They for a triangle link to each other. [BackLinks]
See AutomaticLinkBack for more.