What are "interaction heavy" decks?

I would like to build a deck that is more than average in interacting with the opponents.

But interaction in commander is always a two sided sword, because for each 1 interaction you play you are down a card while the other 2 opponents are not affected.

So I am wondering....in the decks you have played over the years which decks were more focused on interaction than others and WHY was that?

What made you include more interaction in these specific decks? Was it the commander? The colour ? How did the interaction you include lead to your wincondition?