What St Bonney
As long as the server is running, time in the world is passing. Mobs (the term for animals and bad guys) spawn and despawn, trees and crops grow, and fires spread. Everyone who connects shares the same world.
Since this game is basically "Legos" on steroids, you could potentially tear down and steal my stuff, and vice versa. So, there are common courtesies/etiquettes that people should follow else they be banned: namely, don't tear up and steal other people's stuff.
You can't really draw boundaries to say "this area's mine; hands off!"; so, it's all about using your best judgment. You can also attack each other with your tools, and that's also generally frowned-on.
If you want to see two total noobs learning to play on their own shared server, check out that fourth YouTube link (this one
) to get a quick idea of how they can interact.