Write A short note on temporary tables?

Temporary Tables - Temporary tables exists solely for a particular session, or whose data persists for the duration of the transaction. The temporary tables are commonly used to support specialized rollups or exact application processing requirements. Unlike a permanent table, a temporary table does not automatically allocate space while it is formed. Space will be dynamically allocated for the table as rows are inserted.
The CREATE GLOBAL TEMPORARY TABLE command is used to form a temporary table in Oracle.
CREATE GLOBAL TEMPORARY TABLE
(

)
ON COMMIT {PRESERVE|DELETE} ROWS;