Bitcoin Core runs independently from Electrum servers, correct? I mean, a node does not have to connect to a server because its got all the necessary information pertaining to interactions with the Bitcoin network?

My understanding is that an Electrum server needs to be installed on top of a node plus the Electrum wallet? Then, the server operates as a middleman between nodes and wallets to speed up the data interaction process?

I'm not certain these questions make sense. I do have a node package with Electrs installed and been using it a long time and connecting wallets to it but just now am I trying to better understand what I'm using.

The Electrum/EPS/Electrs repos have so far not enlightened me sufficiently. I suppose a diagram would be handy.