There are 2 main types of visas in the US:
Citizens eligible for the United States Visa Waiver Program do not have to apply for a visa to travel to the United States, but they must have an electronic authorization (ESTA) if arriving by air or sea. Visitors can stay in the United States for up to 90 days.
You will apply for a visa for US at a Visa Application Center, US Embassy, or Consulate, depending on the entity accepting the visa application in your country of residence. If not available in your country, you should contact the nearest embassy or consulate.
If you want to apply for the United States Work visa, you must obtain an invitation (letter of acceptance) from an organization or legal entity located in the United States. After receiving the invitation letter, you can apply for the appropriate US Work visa related to your position and job.
Applicants between the ages of 14 and 79 must attend an interview in person with a consular officer. You must bring your appointment confirmation letter.
The interview with the consular officer is the last step which usually only lasts a few minutes. He or she should collect, enter the details and review the application before the interview. Your fingerprint will be scanned electronically.
The questions you will be asked during the interview may relate to your travel plans, the details of your trip (destination, date of departure, hotel where you will be staying, etc.), work, family life, documents, etc., may be relevant to you. There is no standard form or sequence for these questions. In short, the consular can ask you any questions they want about you, your life, and your travels. You may know the answer about your visa at the end of this interview, but additional administrative processing may sometimes be needed.
US Tourist visa fee is USD 160 for all nationalities. Depending on your visa type, fees may vary, or you may have to pay additional fees. You will pay this amount online when you schedule your interview.