What is the visibility of language elements (ie Private vs Public)?

About

The visibility is defined by the private and public keywords where:

• Private elements are hidden from the outside world.
• Public elements becomes the API that is accessible from the outside.

Private / Public may be defined on:

• a module
• class level.
• intern class elements such as a field, method.

Hiding Implementation

A common design pattern is to hide (make private) the most possible element.