Link Rot
Definition
Link rot is the phenomenon of addresses that once worked returning errors or landing on something unrelated. The causes are mundane: a site is restructured and the old paths are dropped, a domain is not renewed, a hosting account is closed, or a shortener goes out of business and takes every code it issued with it. The visible symptom is a 404, but the quieter failure is worse — the address still resolves, only now to a parked page, a new owner's content or a login screen. Studies of academic and news citations keep finding that a substantial fraction of references break within ten years. Nothing warns the person who published the link; it simply stops working.
Why It Matters
A dead link is a broken promise made in public. A QR code printed on two thousand leaflets that lands on an error is money spent on nothing, and leaflets cannot be recalled. Search engines quietly downgrade pages whose references rot, and a dead link in a proposal undermines everything around it. The economics are lopsided: keeping an address alive costs almost nothing, while finding and fixing a rotted one costs someone a morning — assuming anyone notices at all.
How It Works
Rot can strike at any layer of the address. The domain may lapse, in which case DNS no longer resolves the name and nothing else matters. The host may survive while the path changes, giving a 404 unless somebody set up a 301 redirect from the old path to the new one. The file may be replaced by a different file at the same address, which is rot that leaves no error behind and is the hardest kind to spot. Shorteners add a second independent point of failure, since the code and the destination can each die on their own. The defences are dull and effective: keep addresses short and meaningful, redirect rather than delete, and prefer a host whose addresses you control.
Real-World Example
A charity's 2019 annual report was linked from a dozen news articles and hosted on a site that has since been rebuilt twice. Every one of those links is now dead. The 2025 report goes on 99helpers at harborlight-annual-2025.99helpers.site, an address chosen to be readable and to stay put, and the file behind it can be corrected without the address moving. The news links will still work after the next redesign, because they do not depend on it.
Common Mistakes
- ✕Putting dates or version numbers in an address you will need to update — a path ending in v3-final guarantees a v4 and a dead v3
- ✕Deleting an old page instead of redirecting it — every link pointing at it, including the ones you cannot see, breaks at the same moment
- ✕Relying on a free shortener for printed material — if the service stops, the printed code has no fallback and no way of being fixed
Related Terms
Permalink
A permalink is an address meant never to change, so that everything pointing at it keeps working. The permanence is a promise from whoever owns the address, not a property of the web.
Short Link
A short link is a compact URL that redirects to a longer one. It exists to be typed, printed, read aloud or squeezed into a character limit.
QR Code
A QR code is a square barcode that stores a short piece of text, most often a URL, so a phone camera can open it without anyone typing. It is a picture of a link.
301 Redirect
A 301 redirect is a response telling the browser that a page has moved permanently and giving the new address. The old URL keeps working for anyone who follows the old link, but everything that matters now lives at the new one.
URL Slug
The readable, hand-picked part of a web address that names one particular thing — the 'acme-pitch' in acme-pitch.99helpers.site. It is chosen, short and made only of lowercase letters, digits and hyphens.
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