Indian Standard Time (IST)
Indian Standard Time (IST) is the time zone observed throughout India. It is 5 hours and 30 minutes ahead of Coordinated Universal Time (UTC+5:30). IST is used as the official time in India and is the only time zone in the country.

Origin
IST was established during British rule in India as a single time zone for the entire country. Before that, each region in India used its own local mean time. The Indian Standard Time was introduced on 1 January 1906 to bring uniformity in timekeeping across the country.

Geographical Extent
IST is used throughout India, spanning from the westernmost point in Gujarat to the easternmost point in Arunachal Pradesh. It is followed in all states and union territories, including major cities like Mumbai, Delhi, Kolkata, Chennai, and Bangalore.

Daylight Saving Time
Unlike some countries, India does not observe Daylight Saving Time (DST). This means that the time remains the same throughout the year in India. IST is followed consistently without any changes due to DST.

Impact
The uniformity of IST helps in coordinating activities across the country, such as transportation schedules, TV broadcasts, and national events. It also ensures that there is a standard reference point for timekeeping purposes in India.

Conclusion
In conclusion, Indian Standard Time (IST) is the official time zone observed throughout India, established to bring uniformity in timekeeping across the country. It is 5 hours and 30 minutes ahead of Coordinated Universal Time (UTC+5:30) and is used consistently without any changes due to Daylight Saving Time.