Essential Terminology

Multitenant

The Oracle Architecture that consists of a CDB, and one or more PDBs

Container Database (CDB)

A traditional database instance, but has the ability to support PDBs

Pluggable Database (PDB)

A collection of Tablespaces which supports it's own independant Role and User security, and can be easily moved between CDBs

Root Database

The instance administrative layer that sets above PDBs. Users and Roles here must be preceded by c##

Seed Database

A PDB that remains offline to be used as a template for creating new blank PDBs