Linkrot is when you click on a link hoping to find the page on the other end and get a 404 error. It's a problem unique to the internet and completely preventable.
It's an issue now as Google is posed to kill off tens of thousands of adult blogs over the weekend.
The spread of link rot | Felix Salmon
I’m a great believer that once something is placed on the internet for free, it should continue to stay there, for free, unless there’s an extremely good reason to delete it. Back when hosting websites was difficult and expensive, that was easier said than done. But now web hosting is effectively free, there’s really no excuse — and one might hope that, as a result, we’d see less link rot.
But that’s not what’s happening. For one thing, the institution of the permalink is dying away as we move away from the open web; if you’re not even on the web (if, for instance, your content comes in the form of a show on Netflix), then the very concept makes no sense. What’s more, we’ve moved into a world of streams, where flow is more important than stock, and where the half-life of any given piece of content has never been shorter; that’s not a world which particularly values preserving that content for perpetuity. And of course it has never been easier to simply delete vast amounts of content at a stroke. (For instance: the Kanye West and Alec Baldwin twitter feeds.)
The Wikipedia page on link rot says (at the time of writing) that “permalinking stops broken links by guaranteeing that the content will never move” — but in the real world that’s not much of a protection at all. Content management systems change, and when they do, many publishers don’t bother to ensure that the old links still work. (Which is why, for instance, old links to Gawker tend to die, even though the website is still going strong.) And of course permalinking can’t prevent an entire blog from getting deleted — as Google is now threatening to do with certain adult sites.
Small personal blogs die every day, of course, but it’s no protection being owned by a huge media company, either. My boss, Jim Ledbetter, used to edit a site called The Big Money, which was unceremoniously killed off by the Slate Group, its archives lost to history; more recently, Thomson Reuters did the same thing to one of their sites, News and Insight. (The press release announcing the move was one of its victims; a shadow of it lives on here.) When these decisions are made, the fate of the archives never seems to matter; the result is thousands more dead links scattered across the internet every day, pointing to once-valuable resources which no longer exist.