What is COM?

The Component Object Model–COM–is a language-independent binary standard.

That's a mouthful, so let's break it down.  COM provides an agreed-upon (i.e., standard) way of organizing bits (i.e., binary digits; i.e., 0's and 1's) in memory.  Because the standard works at the lowest levels of data storage, it does not rely on any particular language's approach to programming (i.e., it's language-independent).

Basically, COM allows different programming languages to communicate with each other via the universal language of computers: ones and zeroes.

Image by Gerd Altmann from Pixabay

Further reading

What the #$%& is COM!?
One of the most important concepts in VBA is also one of the least understood. Let’s shine a light on the Component Object Model.