im new and i have some questions

[Brayden]

Are all usernames unique where only one account can have one username?

And.

How many people are on Vintage Story right now? How does multiplayer work?

[Stroam]

All usernames are unique and are limited to one per account but display name can be changed by admins on a server.
For published statistics, check the home page.
For multiplayer, any one can setup and configure a server and then give out the connection information for others to join. Information can include server address, password, and mods.

[Streetwind]

To clarify the "server" part:

It is not enough for playing together to have two people who own Vintage Story to click "Multiplayer" in the menu. The game distinguishes strictly between the player (client) and the world (server). When you create a singleplayer game, you will actually spawn an invisible server process in the background, hosted locally on your own machine, and join that server as a client.

Therefore, when two people want to play together, the question of "which world do we play in" must be answered first. That's why you cannot simply put two people together at the click of a button.

There are two options for providing a world. One, either you or your friend can host the world locally on your/their machine, just as it invisibly happens during singleplayer gameplay; only this time, the server will be visible for both yourself and your friend, so that both of you can connect to it. However, your/their home network needs to be set up to allow the kind of outside connections that a Vintage Story server requires - you'll need to research those. Additionally, every person on a server increases the work load that server has to manage. So if your/their computer is already struggling with singleplayer, then trying to host multiple players on a local server will make for a poor experience for everyone involved.

The second option is to use an online server hosting service. The upside is that you don't need to worry about any of the issues mentioned in the previous paragraph. The downside is that you have to pay money to use such a service - usually a monthly fee.