* `+private+`: not accessible outside of their parent classes. If another class needs to log something, it should instantiate its own logger.
* `+static+`: not dependent on an instance of a class (an object). When logging something, contextual information can of course be provided in the messages but the logger should be created at class level to prevent creating a logger along with each object.
* `+final+`: created once and only once per class.
