Question 1

What are the most important HTTP status codes to know?

Accepted Answer

The essential codes are: 200 OK, 201 Created, 204 No Content, 301 Moved Permanently, 400 Bad Request, 401 Unauthorized, 403 Forbidden, 404 Not Found, 422 Unprocessable Content, 429 Too Many Requests, 500 Internal Server Error, and 503 Service Unavailable.

Question 2

What is the difference between 401 and 403?

Accepted Answer

401 Unauthorized means the client has not provided valid authentication credentials (who are you?). 403 Forbidden means the client is authenticated but does not have permission to access the resource (you are not allowed).

HTTP Status Codes & Headers