Timezones

Originally, all time on Earth was some local apparent solar time, the time on a sundial, so every city had its own time. When well-regulated mechanical clocks became widespread in the early 19th century, each city began to use some local mean solar time. The first time zone was created in 1847 by railroads on the island of Great Britain using GMT. Sandford Fleming of Canada proposed worldwide hourly time zones in 1879. By about 1900, almost all time on Earth was in the form of standard time zones, only some of which used a hourly offset from GMT

standard timezones