The process by which Internet links on a website or search engine lead to a URL that is no longer available. A word of advice to any up-and-coming bloggers or Internet writers in general—don't litter your writing with links to external sources because link rot will inevitably set in.
linkrot
n. the gradual fading away of URL links in a web page. (The URLs are replaced by newer addresses or simply are deleted.) After a month or two, linkrot sets in and your links become deadends, one by one.