2xx Success
This category includes all status for a positive Response,
meaning your Request is succesfully fullfilled.
4xx Client Error
When a status code belonging to 4xx category is returned, it indicates that there some kind of error with the request.
For example:
401 Unauthorized (check you are using the api key correctly > )
5xx Server Error
When a status code belonging to 5xx category is returned, it means the server encountered some kind of error while processing your request.