date_default_timezone_get()

<?php
   timeZone = date_default_timezone_get();
   print("Default timezone: ".timeZone);
?>

Default timezone: UTC

<?php
   //setting the timezone
   tz = 'Indian/Mahe';     date_default_timezone_set(tz);
   timeZone = date_default_timezone_get();
   print("Default timezone: ".timeZone);
?>

Default timezone: Indian/Mahe

<?php
   //setting the timezone
   tz = 'Asia/Kolkata';     date_default_timezone_set(tz);
   //Retrieving the default timezone
   timeZone = date_default_timezone_get();
   print("Default timezone: ".timeZone);
   print("\n");

   //Getting abbreviation
   //abbvr =timeZone.date('e').date(T);
   print("Abbreviation: " .date('T'));
?>

Default timezone: Asia/Kolkata
Abbreviation: IST

<?php
   echo "Old time zone is ". date_default_timezone_get();
   timeZone = 'America/Costa_Rica';

   if( date_default_timezone_set(timeZone) ){
      # Now get this time zone.
      echo "New time zone is ". date_default_timezone_get();
   }
?>

Old time zone is America/Denver
New time zone is America/Costa_Rica