Time Zones

• Time zones are geo-political entities
• completely arbitrary, can change at a politician's whim
• Canonical data source: the Olson time zone database
• Each time zone has several parts
• an offset from UTC in minutes and hours
• a name - usually continent or ocean plus city
• America/Toronto
• Europe/London
• some have three component names - America/Indiana/Knox
• Also includes Daylight Saving Time rules
• when do switches happen
• a short name for the zone, like EST