Your character data and world data are two separate things.

You can use your character in any world and it saves all progress and character inventory.

Generally servers are password protected private servers. There are no official game servers run by the devs. So typically you won't have strangers just popping into your game or anything.

Base game has a 10 player limit per server so it isn't like an MMO and people invest time and effort into their worlds and don't really want random people to come in and ruin or steal everything you worked for. That is why most people use passwords.

Originally posted by Darthvegeta800:

Is the world persistant? If say I play with my g/f and a buddy we all can log into the world seperately to keep playing, occassionally team up à la Conan Exiles or is it more that people join in in someone else's world but can't play in it on their own?

unless you're using dedicated server the host keeps the world. and others join him. when you're in you can do whatever you want. even go in defferent directions and never see each other again.
when you're fighting monsters together they get +40%hp and +4%dmg(or something along those numbers) per player in a certain radius (i think it's set on spawn. not dynamic).

Originally posted by Slynx Jewel:

Originally posted by Darthvegeta800:

Is the world persistant? If say I play with my g/f and a buddy we all can log into the world seperately to keep playing, occassionally team up à la Conan Exiles or is it more that people join in in someone else's world but can't play in it on their own?

unless you're using dedicated server the host keeps the world. and others join him. when you're in you can do whatever you want. even go in defferent directions and never see each other again.
when you're fighting monsters together they get +40%hp and +4%dmg(or something along those numbers) per player in a certain radius (i think it's set on spawn. not dynamic).

Pretty sure it is dynamic. In a sense...

The game does things oddly.. not sure if this is normal or not honestly. Typically in co op games I have played everything was based off the host and who joins. Or a dedicated server.

This game basically uses the dedicated server to handle overall stuff but each player can "host" their own area within the game.

So if you split up at the start... each person will be "hosting" the area they are in. As they move around enemies will spawn in and they will be set for single player difficulty.
If one person sets up a portal. Summons a boss in, the boss will only have single player difficulty. Once an enemy is spawned it locks its difficulty to that level. So the other player can then join the other players area and as two players can fight a boss with only one player difficulty. Conversely you can summon a boss with 10 people and have it at 10 player difficulty and everyone may quit leaving one person to deal with a high difficulty boss.

You need to fix your own server so it can be online 24/7, Valheim got that option, when you got this game you can install the server program from steam .
If you want that option that you can walk into the server in anytime without the host is logged on, you need that..

FWIW anyone at all can install the server program from Steam. Owning the game client isn't a requirement. (So if you know any nerds that are already into that kind of thing they could easily host a world for you.)