Чем отличаются уровни доступа public, private, protected и internal в языках программирования?

In C#, access levels determine the visibility of class members:

• public — accessible from anywhere.
• private — accessible only within the same class.
• protected — accessible within the class and its subclasses.
• internal — accessible within the same assembly, i.e., within the same project.

For example, if a class or method is declared as internal, it will only be accessible within the current assembly, but not from other projects, even if they reference this assembly. This is useful for hiding implementation details within a library.