Schema.org is defined as two hierarchies: one for textual property values, and one for the things that they describe.
This is the main schema.org hierarchy: a collection of types (or "classes"), each of which has one or more parent types. Although a type may have more than one super-type, here we show each type in one branch of the tree only. There is also a parallel hierarchy for data types.
An experimental D3-compatible JSON version is also available.