OpenStreetMap is a community project to map the world. Everybody can contribute whatever they want. Or can they? What are the rules that govern what can be mapped in OSM and how? How are we creating a coherent global map and not just a bunch of random data about the world?

For years we have had the "on the ground rule" (really more of a guideline) that helps us decide what and how to map. It has served us well, but it is also sometimes misunderstood. And it is not the whole story. In this talk we want to explore this rule and its many aspects and the other principles anchoring the project in the real world. We want to show how the rule helps avoiding conflicts but also shine a light on where it is sometimes bent and why. We want to figure out what it is that keeps the international and diverse OpenStreetMap community working towards a common goal.