Page Not Found…
What is a “404” error? It occurs when visitors try to access a page that doesn’t exist on your site. If they use a broken link (usually from a renamed/deleted page), they will see a “404 error” message. A custom 404 error page is vital for redirecting lost visitors.
When the 404 was created by Tim Berners-Lee, there were a lot of memes about it. “Page not found” was fodder for comics and a popular t-shirt design. But there’s no secret story behind this code. Website errors fell into the 400 range and “404” was a relatively random assignment for “not found”.