Dead link

A dead link (broken link) is a hyperlink that no longer retrieves the intended resource, typically returning HTTP 404/410, DNS failure, connection errors, or an interstitial that is not the original content. Dead links are the visible symptom of Link rot.

Soft failures

Not all failures are hard 404s. Soft 404 pages return HTTP 200 with a "not found" body; parked domains and malware interstitials can also replace former content. Automated checkers and human editors both struggle with these cases, which is one reason archived captures matter for verification.

In wikis

MediaWiki marks missing internal pages as "red links." External dead links in footnotes undermine verifiability; best practice is to repair, replace with an archived copy, or remove unreproducible claims.

See also

• Link rot
• Soft 404
• Wayback Machine
• Citation

Sources

• Web-engineering and SEO literature on broken-link detection.
• Wikimedia help documentation on external links and link rot (general).