These options include your global database name and system identifier (SID). The SID is a unique identifier that is used to distinguish this instance from other Oracle Database instances that you may create later and run concurrently on your system.
The global database name is the full name of the database that uniquely distinguishes it from any other database. The global database name is in the form database_name.database_domain, for example sales.example.com. The database name portion sales is a simple name you call your database. The database domain portion example.com specifies the database domain in which the database is located. Together, the database name and domain form the global database name.