What is the difference between protected and private in C#?

In C#, protected and private are access modifiers used to control the visibility of members within a class and its subclasses.

The private modifier is used to restrict members to be accessed only within the class where they are defined. This means that only other members within the same class can access private members. Private members are invisible to the outside of the class.

The protected modifier is used to restrict members to only be accessible within the class where they are defined and its subclasses. This means that other members within the same class or derived classes can access protected members. Protected members are not visible to the outside of the class.

Therefore, the main difference is that private members can only be accessed within the class where they are defined, while protected members can be accessed in subclasses of the class.