404 - HTTP Not Found
404 is the web code for 'page not found.'
Why this number matters
It is one of the most seen status codes on the internet.
Background / history
HTTP status codes became standard as the web grew, and 404 became iconic.
Simple example
If a link points to a missing page, the server often returns 404.
Key Facts
- Standard web protocol status code
- Commonly used in custom error-page branding
Fun fact
Many websites design custom 404 pages as a brand moment.