First contact is a term used to describe the first official encounter between representatives of two races or governments. This has become a common factor from two different species from planets, and eventually from alternate universes which led to interdimensional travel and the formations of the Alliance of Nations, the Axis of Empires and the Coalition of Independent States.
Misunderstandings are common in first contact situations, and can lead to unintended and tragic results which often occurred during the Multiverse Wars.