I literally asked what is the social convention for setting up the language that will be used in further conversation. Since I never lived in a country with mu

I literally asked what is the social convention for setting up the language that will be used in further conversation. Since I never lived in a country with multiple languages, I wonder how it is done, especially when multiple people are involved. The convention/algorithm here can be interesting from networking point of view. With 2 people probably some sort of recognition/negotiation is involved first? Maybe person A says "Hello", while person B says "Guten tag" and then the first person knows that they can try to use English or German. But what happens where the group is larger? Also what happens when person A doesnt speak language B and person B doesnt speak language A? How do they negotiate some other language C, since they know few? (obviously some language might be the default) Probably there is some social convention to do that too -> and Im curious how it works, because it sounds like an interesting topic. Do people list the languages that they speak? Or do they have some other clever trick. Still my speculations dont explain how this dynamics work for larger groups, what is an even more complicated topic. The rest of your comment, where you basically wrote that you can recognize what language to use on basis of how a person looks sounds very patronizing, if not racist.