The `dynamic_cast` operator in C++ is used for safely converting pointers or references of base class types to derived class types. It ensures that the conversion is valid at runtime, which helps prevent errors that can occur when dealing with polymorphism. If the cast is not valid, `dynamic_cast` returns `nullptr` for pointers or throws a `std::bad_cast` exception for references. To use `dynamic_cast`, the base class must have at least one virtual function, enabling runtime type identification. This feature is particularly useful in scenarios involving inheritance, where you want to check the actual type of an object before performing operations specific to that type, ensuring type safety in your code.