What is 404

[xiangde]

Search engine via the HTTP status code to identify the state of the web page. When the search engines get a link error, the site should return a 404 status code to tell the search engine to give up the index of the link. If it returns a status code of 200 or 302, the search engine for the link index, which leads to a large number of different links pointing to the same web content. A result, the search engine significantly reduce trust this site. - Many sites exist: 404 pages return a status code of 200 or 302 instead of a 404 status code.