What is the name of the default schema in Oracle?
By default, it is the user you used to log in, and you can query it as below:

select sys_context('USERENV', 'CURRENT_SCHEMA') from dual;


You can change your current schema in your session however:

alter session set current_schema=USER2;


If you create a table after this, without specifying the schema, that table will be created in the USER2 schema regardless of what user you logged on with.