Containing and hiding information about an object, such as internal data structures and code. Encapsulation isolates the internal complexity of an object's operation from the rest of the application. For example, a client component asking for net revenue from a business object need not know the data's origin.

  Inheritance allows one class to reuse the state and behavior of another class. The derived class inherits the properties and method implementations of the base class and extends it by overriding methods and adding additional properties and methods.

 Polymorphism allows a client to treat different objects in the same way even if they were created from different classes and exhibit different behaviors. You can use implementation inheritance to achieve polymorphism in languages such as C++ and Java. Base class object's pointer can invoke methods in derived class objects. You can also achieve polymorphism in C++ by function overloading and operator overloading.

 Constructor creates an object and initializes it. It also creates vtable for virtual functions. It is different from other methods in a class.

  Destructor usually deletes any extra resources allocated by the object.

  Constructor with no arguments or all the arguments has default values.

  Constructor which initializes the it's object member variables ( by shallow copying) with another object of the same class. If you don't implement one in your class then compiler implements one for you.
For example:
  Boo Obj1(10); // calling Boo constructor
  Boo Obj2(Obj1); // calling boo copy constructor
  Boo Obj2 = Obj1;// calling boo copy constructor

  Copy constructors are called in following cases:
  a) when a function returns an object of that class by value
  b) when the object of that class is passed by value as an argument to a function
  c) when you construct an object based on another object of the same class
  d) When compiler generates a temporary object