HTTP status codes are the server’s first sentence.
A status code tells clients what happened before they parse the page. It is one of the fastest ways to separate routing trouble from application trouble.
The useful handful
200 means the request succeeded. 301 is a permanent redirect; 302 is temporary. 404 says a resource was not found, while 410 says it is intentionally gone. 500 indicates a server-side failure and 503 usually signals temporary unavailability.
Redirect with intent
Keep redirect chains short and point old URLs to the closest useful destination. Do not send every missing URL to the homepage. A helpful 404 page can retain navigation while returning a real 404 status.
Pair status with timing
Record the URL, method, status, response time and redirect sequence. Then check application logs. A 200 response with an error message is still a monitoring failure because clients cannot trust the status.