The time zone used in Hawaiʻi, which is 10 hours less than Coordinated Universal Time (UTC) or Greenwich Mean Time (GMT). More formally referred to as Hawaiʻi-Aleutian Standard Time (HAST) since the time zone is shared with that portion of Alaska's Aleutian Islands west of -169.5° longitude. However, the Alaskan portion observes daylight saving time (DST) while Hawaii does not.
info: http://en.wikipedia.org/wiki/Hawaii-Aleutian_Time_Zone