In object-oriented programming, a base class is a class from which other classes can inherit properties and methods. A derived class is a class that is derived from a base class, inheriting its properties and methods.

In C++, a derived class can inherit from a base class using the : operator followed by the name of the base class. For example:

class BaseClass {
// properties and methods of the base class
};

class DerivedClass : public BaseClass {
// properties and methods of the derived class,
// which can also access the properties and methods of the base class
};

The derived class can override or extend the behavior of the base class by defining its own version of a method that is also defined in the base class. The derived class can also add new properties and methods that are specific to it.

One important difference between a base class and a derived class is that a derived class can have only one base class, while a base class can have multiple derived classes. This is known as single inheritance. C++ also supports multiple inheritance, where a class can inherit from multiple base classes.