A broken link is a hyperlink that no longer leads to a working page — usually resulting in a 404 "page not found" error — because the destination page was moved, renamed, or deleted without a redirect.
Broken links can point either to pages within your own site (internal broken links) or to pages on other websites (external broken links), and both create a dead end for anyone who clicks them. Internal broken links are entirely within your control to fix; external ones happen because a site you linked to changed or removed a page you don't control. A 404 status code tells both browsers and search engines that a page genuinely doesn't exist at that URL. This is different from a page that exists but returns an error, or a page that's been intentionally removed and should redirect somewhere useful instead of dead-ending.
Broken links waste crawl activity on dead ends, create a frustrating experience for visitors who hit them, and can quietly waste the value of any links (internal or external) pointing at the now-broken URL. They're one of the most common technical SEO issues on any site that's existed for a while, simply because content naturally gets moved, renamed, or removed over time.
Illumae's site audit crawls your entire site and flags broken links as part of every scan, so you can find and fix them across your whole site rather than discovering them one at a time when a visitor happens to click one.
Internal broken links are worth fixing since they're fully within your control and directly affect visitor experience. For external links you don't control, either update them to a working alternative or remove them if no good replacement exists.
Set up a 301 redirect to the most relevant remaining page, rather than leaving it as a dead 404, so visitors and any existing backlinks still land somewhere useful.
One broken link rarely causes serious harm on its own, but a site with many broken links across it signals poor maintenance to both visitors and search engines, and each one represents a small, avoidable loss of value.
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