Multiplayer Update
From Kerbal Space Program Wiki
The Multiplayer Update is the 5th of 5 planned major updates for KSP2 Early Access.
Features
The Multiplayer Update would add the ability to join a multi-player server and play with friends, either cooperatively or as a space race. 4 space agencies, each with their own space center, would exist on Kerbin. Space agencies could compete against each other, or cooperate by sharing resources.
Multiplayer was originally a planned feature for KSP that has now been moved to KSP2.