A page that Google can't find !. yes that's correct and here is
404 page U.S. Web Design System (USWDS)
Documention
An Analysis of 24 Creative 404 Error Pages - UX Design World
How to Create a 404 Error Page in HTML
404 Page Not Found Error: What It Is and How to Fix It
How to Fix 404 Error in WordPress • Page Not Found [Tutorial
404 error icon flat icon hi-res stock photography and images - Alamy
Why should a 404-error page return the correct HTTP status code
How to edit the 404 Not Found template