Inheritance allows a new class (Derived Class) to inherit the properties and behavior of an existing class (Base Class). It provides code reusability and builds a hierarchical relationship.

Use inheritance when an "IS-A" relationship exists between classes (e.g., a Dog IS-A Animal).

• Object Creation: $O(1)$ (plus base class constructor).
• Call: $O(1)$.

cpp Standard
class Animal {
public:
    void eat() { std::cout << "Eating..." << endl; }
};

class Dog : public Animal {
public:
    void bark() { std::cout << "Barking..." << endl; }
};

int main() {
    Dog myDog;
    myDog.eat();  // Inherited
    myDog.bark(); // Own method
}

• Diamond Problem: Multiple inheritance resulting in ambiguity (use virtual inheritance to fix).
• Forgetting to use public inheritance (defaults to private in C++), making base members inaccessible.
• Not using virtual destructors in the base class when deleting derived objects through pointers.