HTTP Status Codes
Three-digit numbers returned by web servers indicating the result of a browser request.
Status codes tell browsers what happened: 200 = success (page loaded), 301 = permanently moved (redirect), 404 = not found, 403 = forbidden (no permission), 500 = internal server error. The first digit indicates the category: 1xx = informational, 2xx = success, 3xx = redirect, 4xx = client error, 5xx = server error. Knowing status codes helps debug website issues — a 503 means the server is overloaded, a 502 means a gateway problem, and a 504 means the server timed out.