: Redirection errors or server malfunctions.

By default, web servers provide a generic, plain text message like "Not Found". Custom 404 pages are recommended to maintain brand consistency and guide users back to functional areas of a site. 404 Not Found - HTTP - MDN Web Docs - Mozilla

The status code is an HTTP response indicating that a browser (client) can communicate with a server, but the server cannot find the requested resource . It is one of the most recognizable errors on the internet. Core Technical Details

: Changing a URL slug for optimization without updating existing links. Implementation & Customization