Some important codes to know an use:
- 200 (ok)
- 201 created - used when successfully submitting a POST or PUT to the server, indicating something was created on the server
- 400 (bad request) - client error, leading to an malformed request to the server. E. g. a bad form request
- 401 Unauthorized - actually, unauthenticated is the common case here
- 403 Forbidden - payload was actually understood by the server, but server is not allowing the action
- 500 internal server error