Why do we have different time zones?

Before railways, each town set its clocks by the Sun, which caused chaos for train schedules because neighbouring towns could be minutes apart. In 1884, delegates at the International Meridian Conference agreed to divide the world into 24 time zones, each roughly 15 degrees of longitude wide, centred on the Prime Meridian at Greenwich, London. Some countries bend their zones along political borders or use half-hour or quarter-hour offsets. China uses a single time zone across its vast territory, while India is offset by 5 hours and 30 minutes from UTC. Sir Sandford Fleming, a Canadian railway engineer, was one of the strongest advocates for the system.