Buildings are human-made structures with roofs or interior spaces that are permanently or semi-permanently in one place (OSM building definition).
Key Schema Design Choices
In this initial release, we start from a basic model containing footprint polygons and a small number of optional attributes. Attributes currently not covered in the official schema release are allowed to exist with the prefix "ext" in their name. We plan to cover more sophisticated geometries and attributes (e.g. building parts with different heights, detailed 3D models, etc.) in future releases.
Easy transformation from other data sources
Classes such as "residential, commercial, or education" are intended to be broad categories in which many different OSM tagging combinations can map to the same class.