Daylight savings time: not all time zones shift by 1 whole hour, some don't shift at all, some shift by 30 minutes. Confusing, huh?!

Time Zones :)

As answered by Cecil of The Straight Dope Bombay, and India generally, isn't the only place chronometrically out of step with the rest of the world. Lots of countries, particularly in Asia, are a half-hour out of sync, including Burma, Sri Lanka, and Afghanistan. Some have even stranger quirks. If my handy time-zone map here is to be believed--I am a little dubious about some of it--Nepal is 40 minutes off the mark. Saudi Arabia, ever the trailblazer, has some bizarre system in which clocks are supposedly reset to midnight every day at sunset. Keeping one's watch properly attuned aboard the Riyadh-Rangoon express must be an exhausting experience. All of this traces back to the haphazard system of timekeeping prevalent before the 1884 Washington conference that established Greenwich Mean Time (GMT) as the international reference point. The conferees divided the world into 24 zones, the time in each of which was to differ from a whole number of hours from GMT. Prior to this, people made use of "local mean time," i.e., they figured out approximately when the sun was directly overhead, called that noon, and went from there. City A's time would thus differ by some odd number of minutes from that of cities B and C to the east and west. For instance, in 1880, England established two times zones for the British Isles--GMT for England, and Dublin Mean Time, 25 minutes earlier (or later, depending on how you look at it), for Ireland. After the standardization conference, most countries "rounded off" their local time, as it were, so that it differed by a whole hour(s) from GMT and from adjoining time zones. But some, for reasons of geography or politics, rounded off to the half-hour. Newfoundland, for example, was (I think) three hours, 35 minutes, and some seconds behind GMT before standardization, and elected to round off to three hours, 30 minutes--owing, I suppose, to the native perversity of its inhabitants, who delighted in being out of sync with the rest of Canada. India, as it happens straddles two time zones, but for obvious reasons preferred to have one uniform time throughout the country. Rather than choose between GMT+5 and GMT+6 (which would make dawn and dusk in the far reaches of the country either unusually early or unusually late), the government apparently decided to split the difference. I can't explain Saudi Arabia, but nobody else ever has either. http://www.straightdope.com/classics/a1_124.html Here's some more good information that may also be a bit more up to date. http://www.timegenie.com/time http://en.wikipedia.org/wiki/List_of_time_zones http://www.math.nus.edu.sg/aslaksen/teaching/timezone.html

There are many nations that opt to follow a different time zone than is common elsewhere. Some locations opt to observe times that are less than a full hour off of neighbouring time zones -- Nepal for example is a quarter hour off India, which is a half hour off the normal pattern. Nepal does not recognise summer time and never alters the clock during the year. The abnormal time zone settings are not limited to Asia -- the State of South Australia, for example, opts to use a half-hour time zone rather than a full hour.