Php defines implementation code for the 404 page

Php defines the implementation code core code of the 404 page:
The code is as follows:
@ Header ("http/1.1 404 not found ");
@ Header ("status: 404 not found ");
Echo 'echo 404 ';
Exit ();

To load the 404 page, you can run the following code:
The code is as follows:
@ Header ("http/1.1 404 not found ");
@ Header ("status: 404 not found ");
Include ("../404.htm ");
Exit ();

Check whether 404 is set successfully. you can use the firebug plug-in of firefox to check whether is set successfully.

View method

When firebug has been installed, open the 404 status code page in the firefox browser, click the bug icon in the lower right corner, start the "network" tab, and open "network? All/html? Headers "; if everything is normal, you can see various page parameters including headers and responses.

404 page impact on the website

It has little impact on seo. But yes, it is always better than no. If you have this permission, you 'd better set the 404 page. This is similar to the website location. not all websites have to be set, but sometimes it is necessary to set it.
If you want to set a 404 page, you should consider the user experience rather than seo.

Let's take a look at the definition of apache 404.
In apache, setting the 404 error page to set the 404 error page for apache server is simple. you only need to add the following content to the. htaccess file:
Errordocument 404/notfound. php