404 is considered to be one of the common mistakes when doing SEO, but not everyone is aware of this bug and treat them thoroughly. 404 errors occur when broken links and google can not find the boot contents when accessing the website. The fact that a site has too many links 404 will seriously affect the process of website and SEO your website.
Common error messages 404 will in the following form

"404 Error"
"404 Not Found"
"The cầu URL [URL link] was not found on this server."
"HTTP 404 Not Found"
"404 Page Not Found

404 can cause damage to Seo if not handled thoroughly, in addition to the online users are also very annoying bugs and making the site bounce rate increases.

The reason for the 404 on the webiste

There are many causes of this error:
1. Host 1 bunch of dead and made inaccessible page.
2. Set the new code the url for some reason it was gone.
3. User Error 404 misspelled.
4. Due opponent with a series of bad play false path of your domain.
5. ...
His case, 404 appear daily, there are all sorts of reasons, generally very tired every day to check and delete unnecessary false paths.
How to detect 404?

To find out which websites are experiencing is not 404? Can apply the following SEO tips:

Access google webmaster tool and error checking here: https://www.google.com/webmasters/tools/crawl-errors...
Using a number of free tools to find broken links, such as the Internet Marking Ninjas, Link Tiger, W3C Link Checker.
If the user can use wordpress plugin checks as: Broken link checker.

Guide processor 404

1. Create a separate page error message 404
Harmonious design for this page impression is essential.
Eg: http: // bit. VN / uploads / Images / mint_error_page.png

2. Delete Page 404
Remove the 404 pages have been indexed by webmaster tool.
Remove each link in https://www.google. com / webmasters / tools / url-removal ...

3. Use navigation commands (Redirect)
Use navigation commands to navigate the 404 pages about a specific item, usually on the homepage. Where reinstall a new web, there are too many 404 can use robots.txt file blocking notifications every other fault path.

These are instructions on handling common errors when doing SEO 404. One of the effective ways you can help your website to be cleared away all the broken links that the website crashed.