This is an area that is culturally different from the US, in that people do greet one another in German-speaking countries. It is common to enter any business, any building, any "arena" - and greet (be greeted by) folks around you, whether you know them or not!

Because of the understood relationships of "Du" and "Sie" (which you will learn later) - it is easier for people to have a conversation without feeling estranged or like they need to tread on eggshells. As with anything, there are exceptions to every rule, so don't be offended if you run into someone who just doesn't want to talk to you!

Otherwise, --- greet everyone!