HTTP status code
Also called: Status code
The three-digit number in every HTTP response that says how the request went.
Definition
2xx codes mean success (200 OK, 201 Created, 204 No Content), 3xx mean redirection (301, 302), 4xx mean the client made a mistake (400 Bad Request, 401 Unauthorized, 404 Not Found, 409 Conflict) and 5xx mean the server failed (500, 503). Apps decide what to show the user based on them, so returning the right one matters.
In practice
A login with a wrong password should return 401, so the app shows "Wrong password" instead of "Something went wrong".
Learn it in context
Lessons that use this term.