One of the points not discussed in the other replies yet, is that public methods and variables are the interface, the well defined, relatively static way of usi

One of the points not discussed in the other replies yet, is that public methods and variables are the interface, the well defined, relatively static way of using a class. The private members are internal implementation details, and may change frequently -- not to mention completely change in style, functionality and so on. The idea then, is that larger teams can be divided into sub-teams, and work in parallel because the interfaces between components don't change, even if the internals change drastically. Essentially it allows components to be somewhat independent. How this works in practice tho...