That's why I use the "little providers" wording. Most people using email will know, or at least have an idea of, what an email provider is because they had to sign up with one to have said email. It translates easier when trying to teach people what an instance even is.

I don't tend to go as advanced as mentioning that the different Fediverse socials can technically talk to one another (due to all running off ActivityPub). I feel like that just adds a layer of confusion for someone learning, for a feature they may very well not use.

Normally, unless you're insane enough to build a bridge to make that work.
Though if the person I was teaching asked, I'd just say no haha