What are COM-enabled applications?

[Tempo]

As the subject of this post suggests, I have one question; what are
COM-enabled applications? I believe Microsoft Word is one of these
apps, but what else? Is a web browser, Paint, Solitare, games, etc? I'm
not sure if it varies from operating system to operating system, but I
am talking about COM applications in Windows. Thanks for any and all of
your help and time.