404 Not Found

The HTTP 404 status code means a resource doesn’t exist or the server doesn’t want clients to know that it exists.

404 Not Found doesn’t specify whether the resource is temporarily or permanently gone. If you want to signal that the resource was permanently and deliberately removed, use 410 Gone.

Search engines

Upon encountering the 404 Not Found error, search engines eventually remove a page from their indexes, albeit slower than they do with 410s.

Soft 404

In the SEO world, a soft 404 is a page that tells the user it doesn’t exist but returns a 2xx status code. This often happens when the developer serves a custom error page but forgets to set the appropriate status code.

Upon encountering soft 404s, search engines might remove the page from their indexes.