Who and in what cases has the right to contact class members with public access modifier?

The public access modifier in C# means that members of a class with this modifier can be accessed by any other classes and code from anywhere in the project or even from other assemblies (if the member is not restricted by additional attributes).

That is, if a method or field is declared as public, it is accessible:

• Inside the same class
• In other classes within the same namespace
• In classes from other namespaces and assemblies

This is used to define the interface of a class that should be accessible to external code.