COMMIT in PostgreSQL

Hey,

I was running a script which does some INSERTS and UPDATE some table. I
found that there is no need for COMMIT; After each statement the TABLE is
immediately commited. Other session via psql can sees ASAP the changes to
the table. So it seems a bit different than Oracle's COMMIT . Can somebody
explain me why this is so in PostgreSQL ?

Are the modifications done without commit statement ?

PostgreSQL looks really interesting and seems to be good SQL compliant.
stefan