Inheritance is a key concept in object-oriented programming that allows a class to inherit properties and behaviors from another class, known as the base or parent class. The class that inherits these properties and behaviors is called the derived or child class.

In C++, inheritance is implemented using the class keyword followed by the name of the derived class and the base class that it is inheriting from, separated by a colon. Here’s an example:

#include <iostream>

// base class
class Shape {
public:
  void setWidth(int w) {
    width = w;
  }

  void setHeight(int h) {
    height = h;
  }

protected:
  int width;
  int height;
};

// derived class
class Rectangle: public Shape {
public:
  int getArea() {
    return (width * height);
  }
};

int main() {
  Rectangle rect;

  rect.setWidth(5);
  rect.setHeight(7);

  std::cout << "Area of rectangle: " << rect.getArea() << std::endl;

  return 0;
}

In this example, we define a Shape base class with two protected data members width and height and two public member functions setWidth and setHeight for setting these data members. We then define a Rectangle derived class that inherits from the Shape base class using the public keyword.

The Rectangle class has a single member function getArea that calculates the area of the rectangle using the width and height data members inherited from the Shape base class.

In the main function, we create an object rect of the Rectangle class and call the setWidth and setHeight member functions to set the width and height of the rectangle. We then call the getArea member function to calculate and print the area of the rectangle.

Inheritance allows us to reuse code and avoid duplicating similar functionality across different classes. It also enables us to create more complex class hierarchies and models for our programs.