Broken Link
Definition
A broken link is a hyperlink whose target no longer resolves to the content it was written for. The usual symptom is a 404 response, returned when the path in the link matches nothing on the server; a 403, a dead domain or an expired share link produce the same dead end from the visitor's side. Broken links come in two kinds. Internal ones point at your own pages and files, and are entirely your fault and entirely your fix. External ones point at somebody else's site that has moved, closed or reorganised, and you only find out by checking. There is also the quiet case where the URL still returns 200 but the content behind it has been replaced by something unrelated, which no automated checker will flag. The durable fix for a page you moved is not to hunt down every link to it but to record the old address in a redirect map.
Why It Matters
A broken link is a visitor who arrived with a clear intention and got nothing. On a page of external references that has been up for three years, it is normal to find a tenth of them dead — the slow decay usually called link rot. Internally the cost is sharper: a dead link to your price list, on a page people reach from an email campaign, wastes the whole campaign. Search engines also read a run of 404s as a sign that a site is unmaintained, and a crawler that keeps hitting missing URLs spends its budget on nothing.
How It Works
A link checker crawls your pages, pulls every href and src out of the HTML, and requests each target — normally a HEAD request first, falling back to GET when a server refuses HEAD. The response status is the verdict: 200 is healthy, 301 or 302 means the target moved but still resolves, 404 means missing, 410 means deliberately removed, and a connection timeout or DNS failure means the host itself has gone. Checkers usually run on a schedule and report a difference, so you see what broke since last week rather than the same long list every time. Anchor-only links such as '#pricing' and mailto: links need excluding, or they fill the report with noise. Whatever slips through gets caught by a custom 404 page that offers a search box and a route back to the home page rather than a bare server error.
Real-World Example
A design studio publishes a 6 MB portfolio PDF at studio-work.99helpers.site/portfolio.pdf and links to it from three case study pages. Six months later they rename the file to portfolio-2026.pdf, and all three links start returning 404 — as does the version pasted into two client emails. Running a checker over the site finds the three internal ones in a minute. The emailed links are only rescued by putting the old path back, or by redirecting it to the new file, which is why renaming a published file is worth thinking about twice.
Common Mistakes
- ✕Checking only internal links — external targets rot fastest, and nothing tells you when a third-party page quietly disappears
- ✕Renaming or reorganising files after publishing without leaving a redirect behind — every link anyone has already shared dies at once
- ✕Treating a clean checker report as proof everything works — a link that returns 200 but now points at a parked domain still fails the reader
Related Terms
Redirect Map
A list of old URLs paired with the new addresses they should send visitors to. It is the record you keep when you move, rename or retire pages, so links that already exist in the world keep working.
Content Audit
A systematic review of everything you have published: what each page is, when it was last touched, whether it is still accurate, and whether anyone reads it. The output is a list with a decision recorded against every row.
Link Rot
Link rot is the slow decay of working links into dead ones as pages move, domains lapse and services shut down. A large share of links published a decade ago no longer resolve.
Custom 404 Page
A custom 404 page is the page a site shows when someone asks for an address that does not exist, written by you rather than left to the host's default. It is returned with a 404 status code.
HTTP Status Code
An HTTP status code is the three-digit number a server returns at the head of every response, saying what happened to the request. It is the first thing on the first line — a 200 means here is the file, a 404 means there is nothing at that address.
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