Tourist B2 Visa Query (New York)

Hi Everyone,

According to my aplication, the customs officer at the airport gave me a one year stamp on my B2 Visa ( Tourist visa).

I was surprised because normally, the B2 visa has to be extended after 6months for 6 months more.

I d like to know if someone has the same Visa than I?
I am also wondering if after one year staying here I can come back to US with another VISA.

Official information about Visa are very dificult to find, if you have any advice, feel free to share them with me :)

Thank you!