HTTP status codes are the three-digit numbers a server returns to describe the outcome of a request:
- 2xx — success (e.g. 200 OK)
- 3xx — redirection (e.g. 301 Moved Permanently)
- 4xx — client errors (e.g. 404 Not Found)
- 5xx — server errors (e.g. 500, 503)
Monitoring on status codes is the baseline for website and API checks — though a 200 alone doesn’t guarantee the content is correct, which is why keyword and body assertions matter.
