alt Hacker NewsVisa renewals are processed at a US consulate. You can extend your status (ie you ability to legally be in the US) while staying in the US, but if you want to renew your visa (your ability to leave and re-enter) you need to visit a consulate and those only exist outside of the US.
I was questioning the renewals every six months and asking about US visas which are granted for 6 months (i.e. expire after 6 months). I am aware of renewals requiring leaving the country.