What are the three logical sets of tables that make up a PeopleSoft database and what is the purpose of each?

System Catalog Tables– This table contain metadata about all object in the database.
People Tools Tables—This table contain the metadata about PeopleSoft that is installed on the database. And also the structure that applications use to define specific objects. The structure of the tables is the same for all applications.
Application Data Tables— This table contain data entered for use by your organization. Any table updated ad part of a component is an application data table.