As of February 2015, visas into the United States for the purpose of tourism, visiting or business must be completed online via a nonimmigrant visa application, form DS-160, according to the U.S. Department of State. The application is submitted to the U.S. Embassy or consulate in one's country of residence.
A nonrefundable visa application fee is required with the submission of an application, instructs the U.S. Department of State. Additionally, a current, color photo that meets visa guidelines is uploaded with the application. An interview is required for the majority of applicants. Although applicants under the age of 13 and over the age of 80 generally are not required to attend an interview, consular officers have the right to require an interview of any applicant, regardless of age.
The interview takes place at the U.S. Embassy or consulate located in the country of the applicant's residence, adds the U.S. Department of State. Documents the applicant needs for the interview include a passport valid for travel at least six months beyond the period of stay, a copy of the DS-160 application confirmation page and receipt of fee payment. Additionally, the applicant may be asked for documentation establishing the purpose of the trip, intent to return to the home country and ability to pay for travel expenses.
It's further advised by the U.S. Department of State to not make any travel plans until the visa is approved. An interview doesn't guarantee visa issuance.