A request always gets an answer, even when the answer is bad news. The answer arrives as a status code.
The tag below points at images/missing.png, a file that is not
on the server. The request still happens; it just comes back 404 Not
Found, shown in red in the Network tab. That is why you see a broken image
icon instead of a picture.
The same thing happens when you click a link to a page that does not exist. Try this link, then look at the status of the new row: 404 again, and the server sends back an error page instead of the page you wanted.
| Code | Meaning |
|---|---|
| 200 | OK — here is the file |
| 304 | Not Modified — your cached copy is still good |
| 404 | Not Found — no such file on this server |
| 403 | Forbidden — it exists, but you are not allowed it |
| 500 | Internal Server Error — the server broke |