Often times when we are accessing a web page appears An error message 404. Error message
404 is a general website that shows the error on the web page, usually when the link is lost / damaged or page not found then this message appears frequently. Some websites display a 404 page error costum, which may look similar to other pages on the site. Other sites show only a standard Web server error message text, which usually begins with a “Not found. ”
So why call it a “404 error” instead of “Missing Webpage Error?” The reason is because the 404 is the error code generated by the Web server when it can not find a web page. Error codes are recognized
by search engines (search engines), which helps prevent search engine crawlers index the URL is bad. 404 errors can also be read by a web script and site monitoring tools, which can help webmasters find and fix broken links.
Other common Web server code is 200, meaning a web page has been found, and 301, which indicates the file has been moved to a new location. As in the case of error 404, error status messages are not seen directly by the user, but they are used by search
engines and software monitoring a website.
so from the picture above we can conclude that our error message “404 not found” is not the fault of the user’s web browser, but it is the fault of the website or blog is concerned, the admin may have to delete or move a valid address of a link / URL address of a website.