What Are the Predefined Tablespaces in a Database? - Oracle DBA FAQ - Managing Oracle Tablespaces and Data Files

When you create a new database, Oracle server will create 4 required tablespaces for the new database:

• SYSTEM Tablespace - Every Oracle database contains a tablespace named SYSTEM, which Oracle creates automatically when the database is created. The SYSTEM tablespace is always online when the database is open.
• SYSAUX Tablespace - The SYSAUX tablespace was installed as an auxiliary tablespace to the SYSTEM tablespace when you created your database. Some database components that formerly created and used separate tablespaces now occupy the SYSAUX tablespace.
• UNDO Tablespace - UNDO tablespaces are special tablespaces used solely for storing undo information. You cannot create any other segment types (for example, tables or indexes) in undo tablespaces. Each database contains zero or more undo tablespaces. In automatic undo management mode, each Oracle instance is assigned one (and only one) undo tablespace. Undo data is managed within an undo tablespace using undo segments that are automatically created and maintained by Oracle.
• TEMP Tablespace - When the SYSTEM tablespace is locally managed, you must define at least one default temporary tablespace when creating a database. A locally managed SYSTEM tablespace cannot be used for default temporary storage.