Pencil 404 Yellow Website Template

HTTP 404 or Not Found error message is one of HTTP's "standard response messages" (HTTP status code). This message means that when the client is browsing the web, the server cannot provide information normally, or the server cannot respond and the reason is unknown.
Customizing 404 error pages is a good practice to enhance user experience, but the impact on search engines is often not noticed during the application process. For example, incorrect server-side configuration results in returning a "404" status code or a custom 404 error. Using Meta Refresh on the page causes the "302" status code to be returned. A properly configured custom 404 error page should not only display correctly, but also return a "404" error code instead of "200" or "302". Although it makes no difference whether the HTTP status code is "404" or "200" to the visiting user, it is very important to the search engine.
When a search engine spider gets a "404" status response when requesting a URL, it knows that the URL has expired, and will no longer index the web page, and feedback to the data center to delete the web page represented by the URL from the index database. Of course, The deletion process may take a long time; when the search engine gets the "200" status code, it will think that the URL is valid, index it, and include it in the index database. The result is this Two different URLs have exactly the same content: the content of a custom 404 error page, which causes duplicate webpage issues. At worst, your ranking will be demoted by search engines, and at worst, your website will be deleted.