Game flow states

Heya, I have noticed that there are a lot of things that I don’t quite understand yet. It seems like there are Rounds, Lobbies, Matchmaking, something called “pre-game” and similar things.

I couldn’t really find any documentation about it. Is there maybe some sort of game flow state graph anywhere?

Like… I simply preview my UEFN project and am in the world - I have no clue what “Rounds” and similar keywords are actually referring to, where matchmaking takes place and similar.