date_default_timezone_set Sets the default timezone used by all date/time functions in a script &reftitle.description; booldate_default_timezone_set stringtimezone_identifier date_default_timezone_set sets the default timezone used by all date/time functions. Since PHP 5.1.0 (when the date/time functions were rewritten), every call to a date/time function will generate a E_NOTICE if the timezone isn't valid, and/or a E_STRICT message if using the system settings or the TZ environment variable. 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; timezone_identifier The timezone identifier, like UTC or Europe/Lisbon. The list of valid identifiers is available in the . &reftitle.returnvalues; This function returns &false; if the timezone_identifier isn't valid, or &true; otherwise. &reftitle.changelog; &Version; &Description; 5.1.2 The function started to validate the timezone_identifier parameter. &reftitle.seealso; date_default_timezone_get