Originally posted by Seba:

I was wondering if there's any way to transfer the world so he can host.

Next time don't just wonder around and just search[duckduckgo.com]... (btw. I just typed "valheim copy world" the "from friend" was a suggestion)

Valheim world save locations.
You decide in-game where a world is stored/saved.
https://store.steampowered.com/account/remotestorageapp/?appid=892970

With 0<X<=4 - The default max.=4 can be changed in VH's Misc menu.

Just copy the relevant world files, 7zip them and send them to your friend.

Friend can then unpack them in "NEW:" (I recommend against using the Steam cloud) and use them directly.
If that doesn't work: 1. Friend create world with same name. 2. Switch to locals save. 3. Overwrite said save with your backup (while VH isn't running).

Originally posted by Seba:

Originally posted by Bergman:

yes, by the seed-code

Does that save anything? Like buildings or boss progress?

Nothing. The world seed is just that. The seed used by VH's world generation algorithm. -> Even with the same Seed you'd get a different world today compared to ~a year ago.