Link rot is the process by which links on a website gradually become more irrelevant as time goes on. This is because the websites or pages linked may go down, change content or redirect to a new location.

It also describes the effects of leaving webpages un-updated for some time. That is, they become out of date and the information they consist of becomes old and eventually next to useless, simply cluttering up search engine results. This is perhaps more frequently occurring in personal homepages that the owner has lost interest in. http://geocities.yahoo.com hosts what are often fine examples of such rot.