date_default_timezone_set Sets the default timezone used by all date/time functions in a script &reftitle.description; booldate_default_timezone_set stringtimezoneId date_default_timezone_set sets the default timezone used by all date/time functions. Instead of using this function to set the default timezone in your script, you can also use the INI setting date.timezone to set the default timezone. &reftitle.parameters; timezoneId The timezone identifier, like UTC, Africa/Lagos, Asia/Hong_Kong, or Europe/Lisbon. The list of valid identifiers is available in the . &reftitle.returnvalues; This function returns &false; if the timezoneId isn't valid, or &true; otherwise. &reftitle.examples; ]]> &reftitle.seealso; date_default_timezone_get