When it is better to use "timestamp without time zone"? - Mailing list pgsql-general

Greetings,

Happy New Year listing!

I have a question about column type timestamp "with time zone" and
"without time zone".
. when data are import/export into different time zones, column
timestamp with time zone is necessary
  For example, "2005-01-01 2001:01:01+05" under timezone1 will still be
saved as "2005-01-01 2001:01:01+05" under different time zones
  Otherwise, "2005-01-01 2001:01:01" means different timestamp under two
different time zones

I need to know when it is better that we use "timestamp without time
zone" ? And when it is better to use "timestamp with time zone"?

Thanks a lot!
Emi