404 Not Found is the HTTP status code a server returns when nothing exists at the address requested. The visitor sees an error page, and search engines learn that there is no content to index at that URL.
How a 404 works
Every time a browser or crawler asks for a URL, the server replies with a status code before any content. A 200 means “here is the page”; a 404 means “there is nothing here”. The page the visitor sees can be as friendly and well designed as you like, but the code underneath must still be 404. If the server shows a “page not found” message while returning 200, search engines see a real page with almost no content, which Google classes as a soft 404.
404s come from ordinary causes: a page deleted without a redirect, a URL changed during a redesign, a typo in an internal link, another website linking to a slightly wrong address, or bots probing for URLs that never existed. Google recrawls 404 URLs now and then for a while in case they come back, then visits them less and less.
Google has said repeatedly that 404s are a normal part of the web and do not harm the rankings of the rest of a site. A shop that retires products or a venue that removes last season’s events will always have some.
Why it matters
The useful question is not “do I have 404s?” but “are any of them costing me something?” Three cases are worth fixing:
- Pages that had links from other websites. Those links now point at nothing, so their value is lost. A 301 redirect to the closest equivalent page recovers it.
- Pages that still get visits. From old emails, social posts, printed leaflets or bookmarks. Each visit is a potential customer meeting a dead end.
- Broken internal links. Your own site sending people and crawlers to missing pages, which wastes their time and weakens your internal linking.
Paid traffic adds a direct cost. If an ad’s final URL returns a 404, Google Ads will typically disapprove the ad for a destination that does not work, and until then you may be paying for clicks that land on an error.
Common mistakes
- Redirecting every 404 to the homepage. Plugins offer this as a “fix”. It confuses visitors and Google usually treats it as a soft 404 anyway.
- A custom error page that returns 200. It looks right to people and wrong to search engines.
- Panicking over reports. Search Console lists 404s for URLs that bots invented or that were removed years ago. Most need no action.
- A bare error page. A message with no navigation, search or contact details turns a missing page into a lost visitor.
- Leaving internal links broken after a restructure. These are entirely within your control and the quickest to fix.
How to act on it
Open the Page indexing report in Search Console and look at the “Not found (404)” list. Sort the URLs into groups: pages with backlinks (check them in your link tool), pages with recent traffic in analytics, and everything else. Redirect the first two groups to their closest live equivalents. For pages with lost links but no natural replacement, link reclamation means asking the linking site to update the URL.
Crawl the site to find and correct broken internal links at source. Then make your 404 page helpful: a plain explanation, a search box, links to your main services and a phone number. Finally, track views of the error page in GA4, so a sudden rise after a change gets noticed quickly. Finding and prioritising these is a standard part of my technical SEO work.