What is a 404 page?
In 1992, Tim Berners-Lee defined all the HTTP (Hypertext
Transfer Protocol) codes based on the FTP (File Transfer Protocol)
status codes. If you break it down, the first 4 indicates the error
is a client error, the 0 indicates a general syntax error, and the
final 4 refers to the specific error code in the 4xx group of error
codes. In total there are 17 error codes in the 4xx group.