The Google Cloud Platform Hierarchy is a internal platform resource hierarchy is something you should go out bottom up.
Whatever the resources utilized they are VM’s, cloud storage buckets, tables and big query, they are all organised into projects.
- Projects rollup into folders.
- Folders can also multiple other folders.
Together everything can rollup into an organisation node.
GCP Resources -> Projects -> Folders -> Organisation Node
Policies can be enforced at any level of this tree.