COM or the Component Object Model is a specification.
The COM standard defines the following;

A common way for applications to access and perform operations on Objects.

A mechanism for keeping track of whether an object is in use and deleting it when it is no longer needed.

A mechanism for applications to exchange objects

A way to identify objects and to associate them with applications that understand how they are implemented.

(excerpt from DAN APPLEMAN - Developing COM/ACTIVEX Components)