The world has 24 time zones. Some regions, countries or states usually shift their times by half an hour from the 24 hour time zones or divisions. Standard inside most time zones is a number of hours offset from a time scale( Coordinate Universal Time) usually abbreviated UTC. To convert UTC to local time some hours should be added or subtracted from UTC. For example, the following conversions apply for the United States: Atlantic Daylight Time - subtract 3 hours from UTC Hawaii-Aleutian Standard Time - subtract 10 hours from UTC Central Standard Time - subtract 6 hours from UTC Pacific Standard Time - subtract 8 hours from UTC Samoa Standard Time - subtract 11 hours from UTC Pacific Daylight Time - subtract 7 hours from UTC