The script for creatiung temporary table is:

CREATE GLOBAL TEMPORARY TABLE EMP_TMP
( EMPNO NUMBER,
EMPNAME VARCHAR2(50))
ON COMMIT DELETE ROWS;

A session / transaction can insert data into this temp table. Once the transaction ends, the rows are no longer available for SELECT. Note ON COMMIT DELETE ROWS clause.
The other benefit is:
The inserted rows by one session/transaction can not be availble for another session.
You do not need to commit after inserting rows into TEMP table.