Need for "Virtual Destructor"

If we have 2 classes, say

class CBase{
public:
CBase(){}
~CBase(){}
};

class CDerived : public CBase{
public:
CDerived(){}
~CDerived(){}
};

and if we do,

CBase* pBase = new CDerived;
delete pBase;

Since CBase does not have a virtual destructor, the delete pBase invokes the destructor of the class of the pointer (CBase::~CBase()), rather than the destructor of the most derived type (CDerived::~CDerived()). And as you can see, this is the wrong thing to do in the above scenario.

A class must have a virtual destructor if it meets both of the following criteria:

• You do a delete pBase.
• pBase actually points to a derived class object.