In C#, what is the difference between public, private, protected, and having no access modifier?

Question

All my college years I have been using public, and would like to know the difference between public, private, and protected

Answer 1

Careful watch your accessibility of your classes. Public and protected classes and methods are by default accessible for everyone.

Also Microsoft isn't very explict in showing access modifiers (public, protected, etc.. keywords) when new classes in Visual Studio are created. So, take good care and think about your accessibility of your class because it's the door to your implementation internals.