How US Visa Process works?

In General a person gets a H1B Visa for 6 Years. It may be sometimes less time also 2 Years or 3 Years also based on decision of US Consulate.

After 6 Years the person becomes eligible for Green Card in US, then they apply for Green Card it may take 1 year or 10 year or 50 years for the approval of Green Card.

Till then the person gets i797 for 1 year or 2 years and they can keep renewing it.

What happens when the person applies for i797 or i797 extension?

So when a person applies for i797 extension the US consulate will extend it as per their wish lets say 1 year or 2 year etc.,

But in case the Indian Passport is valid for lets say 6 months only, then the i797 extension will happen only for that 6 months.

So if a person has i797 renewal in short due then they will try to renew their passport so that they will get full term benefit in i797 renewal.