Link rot is the process by which hyperlink on a website gradually become more irrelevant or broken as time goes on, because the websites that are linked to disappear, change content or redirect to a new location.
The phrase also describes the effects of failing to update webpages so that they become out-of-date, containing information that is old and useless, and that clutters up search engine results. This process most frequently occurs in personal Homepages that the owner has lost interest in, and is prevalent in free webhosts such as GeoCities, where there is no financial incentive to fix link rot.
Several notable web designers, such as Jeffrey Zeldman and the influental web designer magazine A List Apart list various techniques web designers can employ to prevent link rot. One solution is a permalink system, that is, a system that is designed with the fluidity of the web in mind and ensures that links on a server remain permanent and unchanging. This does not stop link rot, as sites still are taken down entirely from time to time, but can slow it significantly.
The .
=Combating Link Rot=
A number of basic rules can help webmasters to reduce link rot, including:
Do not keep a hyperlink collection unless you are willing to look after it.
Design your hyperlinks so that you can maintain them. A central hyperlink collection is easier to service than hyperlinks that are scattered throughout a large website.
Do not link to sub-pages ( deep linking ) unless you are confident that they will remain stable.
Use hyperlink checker software or a Content Management System (CMS) with link checking included.
Check hyperlinks on a regular basis. 3-4 times a year should be the minimum.
Use permalinks.
Assign somebody to link maintenance and make sure he understands his reponsibilities.
Put the right e-mail address or other contact information on the same page where the links are with specific information ( Found a bad link Contact and we ll fix it. )
When changing domains, help others fix their link pages by spreading the information well ahead of the migration, and use List_of_HTTP_status_codes to communicate that a page has moved (eg. 301: Moved Permanently ).
=External links=
[http://www.w3.org/Provider/Style/URI Tim Berners-Lee on link rot]
[http://www.useit.com/alertbox/980614.html Jakob Nielsen on link rot.]
=Studies of Link Rot in Academic Citations=
[http://www.iwaw.net/05/papers/iwaw05-mccown1.pdf The Availability and Persistence of Web References in D-Lib Magazine by Frank McCown et al.]
[http://doi.ieeecomputersociety.org/10.1109/2.901164 Persistence of Web References in Scientific Research by Steve Lawrence et al.]
[http://portal.acm.org/citation.cfmid=602422 The Decay and Failures of Web References by Diomidis Spinellis]
