Sometimes we need to limit access to class attributes, so that it can be accessed only from the class itself. This concept is called **encapsulation**.
Dart allows making attributes **private**, meaning that they can be accessed or modified from the class instance. Attributes are made private with a leading underscore (`_`) on the name of the method or attribute.
> But... There is no encapsulation at the `class` level in Dart. The encapsulation is rather applied at the scope of the library which contains the class.
Importing libraries can help you create a modular and shareable code base. Libraries not only provide APIs, but are unit of privacy: private variables, i.e. starting with an underscore (`_`) are visible only inside the library. Every Dart app is a library, even if it doesn’t use a library directive.
