Why Indian Standard Time ahead of San Francisco Time?

Answer 1

Because San Francisco is behind India. Simple!

That's the direction in which the earth rotates, and the International Date Line was put where it is because that's the most sparsely populated part of the planet.

Answer 2

Indian Standard Time (IST) is ahead of San Francisco Time (PDT) because of their geographical locations on the globe. India is located to the east of San Francisco, which means that the sun rises and sets earlier in India compared to San Francisco. Time zones are defined based on longitudinal differences, so areas to the east of a reference point will typically be ahead in time.

Answer 3

Each country makes its own rules regarding in what time zone(s) they are.