Comment by asveikau

> I couldn't figure out how to use COM or what it's purpose was.

A shorter version than the other reply:

COM allows you to have a reference counted object with callable virtual methods. You can also ask for different virtual methods at runtime (QueryInterface).

Some of the use cases include: maybe those methods are implemented in a completely different programming language that you are using, for example I think one of the historical ones is JavaScript or vbscript interacting with C++. It standardizes the virtual calls in such a way that you can throw in such an abstraction. And since reference counting happens via a virtual call, memory allocation is also up to the callee. Another historical use case is to have the calls be handled in a different process.