Ark offers private servers for you to build and maintain your base and interact with several other players and non-playable creatures in its game world. To host a private server for you and your friends, you need to simply create one in the Host/Local menu, choose your settings however you like, and invite whoever you want to play with! However, do take note that hosting a private server on Ark takes up a lot of your RAM and processing power. And your experience might not be the best, due to the poorly optimized server software.