Wikipedia:Link rot

Like most large websites, Wikipedia suffers from the phenomenon known as link rot, where external links become dead, as the linked web pages or complete websites disappear, change their content, or move without HTTP redirection. URLs have a median lifespan of about 1 year.

Link rot is a significant danger to Wikipedia because of the reliability policy and source citation guideline.

In general, do not delete cited information solely because the URL to the source does not work any longer. Tools, procedures, and processes are available as outlined in this document.