404 Error

A 404 Error (Not Found) is an HTTP status code indicating that the server could not find the requested webpage. While Google has explicitly stated that 404 errors are a normal part of the web and do not inherently trigger algorithmic penalties, they are disastrous for user experience and link equity. If a page with valuable backlinks returns a 404, all the authority flowing into that page is completely lost. Every high-value 404 error must be immediately identified and 301 redirected to the most relevant, active commercial page on the domain.

404 Error Simplified

A 404 error is a dead end. It means someone clicked a link or typed in a web address, but the page they were looking for no longer exists. If other websites are linking to that dead page, you are losing all the SEO value those links provide.