shared_ptr<> is most useful for multithreaded applications where a pointer can be safely shared amongst many threads, where the last one to go out of scope will

shared_ptr<> is most useful for multithreaded applications where a pointer can be safely shared amongst many threads, where the last one to go out of scope will call delete on the object. To do this safely the shared_ptr<> class maintains a reference count which is protected by a mutex. This is pretty inefficient if you never share a pointer across threads. Better to use unique_ptr<> where the Thing that created it is also the Thing that's responsible for deleting it - after making sure that anything it's shared the pointer with is already safely destroyed (another thread, a collection or some other object).