US Visa

A stay in the US for purposes of education, research, employment, medical treatment or vacation for a foreign national requires the procurement of a US visa without which no foreigner will be entertained entry in to the US. US Visa Waiver Program is offered to citizens of select counties. The countries who qualify for the US Visa waiver Program in most cases can enter the US without a US Visa for a period of 90 days.

Nonimmigrant Visa:
Nonimmigrant US Visa is issued for any traveler to the United States for the purpose of work, study, vacation or visit. The purpose of the visit should be for a temporary period. The intention of the visit should not be for permanent residence in the United States.
Normally applicants who intend to get a nonimmigrant US visa will have the interview scheduled by the consulate. Walk-in applications are not entertained.
The applicants between ages 14 to 79 are required to attend the interview.
Successful applicants who qualify for the US visa would be required to submit the passport to the consulate. The process of having the visa stamped would take 5 business days, until then the passport would remain with the Embassy and the same will be returned when the Visa is issued.
Some applicants may require further verification after the initial interview; for such cases the US visa processing may take additional time.

Immigrant Visa:
Immigrant US Visa is meant for people who wish to stay for long in the US. This visa qualifies one to stay in the US permanently whether or otherwise the applicant seeks employment or not.
The USCIS provides immigrant visa via marriage or immediate relatives, immigrant visa for employment, immigrant visa for people who did qualify via the Diversity Lottery Program.
Immediate relatives like spouse, children, step-children, parents, step-parents of a U.S. Citizen or green card holder are eligible to apply for immigrant US Visa.
Family relatives like unmarried son or daughter above 21 years of a US citizen, brother or sister of a US citizen, married daughter or son of US citizen also qualify.
In all stances the applicant US citizen should be above 21 years of age.
Employment based immigrant visa is given after due labor certification from the DHS. There are stringent rules to qualify under this category after which the immigrant visa is issued.