Inheritance involves a base class and a derived class. The derived class inherits from the base class. With few exceptions, members of the base class are inherited into the derived type. Derived classes can override inherited members and add new members to extend the base class.

Here is the inheritance syntax:

class derivedclass: baseclass, interface1, interface2, ...,  interfacen {
    body
}

In the class header, the inheritance operator (:) indicates inheritance and is followed by the inheritance list. The inheritance list is a comma-delimited list that includes a maximum of one base class and any number of interfaces. Classes are limited to inheriting a single class. However, a class can implement multiple interfaces. C++ developers are familiar with multiple base-class inheritance. Omitting this feature from C# was an important design decision. First, multiple inheritance was never that popular. Second, multiple inheritance often causes more problems than it resolves. Third, multiple inheritance introduces the potential for member ambiguity.

A base type must have the same or greater accessibility as the derived type. A compiler error occurs in the following code because the accessibility of the base class is narrower than the derived class, which is an error:

internal class ZClass {
}
public class YClass : ZClass { // Error
}

.NET supports only public inheritance. C++ supports public, protected, and private inheritance. Despite this flexibility in C++, practically all inheritance is public inheritance. Most C++ developers were not familiar with or ever used any other kind of inheritance. Thus, protected and private inheritance probably will not be missed.