Error 404 or «Error 404 Not Found» is a standard response code of the server when a user tries to click a link that doesn't exist. Thus the user is informed that the requested page does not exist. Error 404 is a perfectly workable situation and, as a rule, it does not indicate a problem with the site. A 404 error usually indicates:
- a mistake made while entering the URL of the page;
- deletion of the page by the site owner;
- a change in the URL of the page.
Faced with a 404 error, the user enters a special page. The page can be standard, which only says «Error 404», or customizable. The custom page with error 404 is stylized under the general design of the site. On it, in addition to the message «Not found» may be an explanation of the situation — why this happened and what the user can do. The page can also have a search line or site map so that the user can still find what he is looking for. Often companies add an element of entertainment to a 404 error page to smooth things over. This can be a joke phrase, an interesting image, or some other trick.
If the cause of the 404 error is not a typo in the address, but a change in the URL of the page by the site owner, this problem can and should be fixed. Otherwise, it will lead not only to the dissatisfaction of users but also to the loss of the page in the organic search. To fix the error site owners need to set up redirects to the new address so that when you enter the old URL, the user will still get to the right page.
You can find pages with 404 errors using Google Search Console. The owner of the site will scan the resource for errors and see all the pages that are not found. In addition to this tool, there are other services to scan the site, but Google Search Console is free and easy to use.